To many people in the developing world, the lack of safe and sanitary toilets remains a daily reality.

In India, the lack of toilets is so severe that Prime Minister Narendra Modi has made building toilets a national priority. We wonder: Which of the following statements about India’s lack of toilets is true?

A. 60% of all households without toilets in the world are in India.

B. India’s Muslims are less affected by the sanitation problem than Hindus.

C. India’s lack of toilets is worse than China’s.

D. Lack of toilets in India puts women at especially high risk.

A. 60% of all households without toilets in the world are in India is true.

Despite rising incomes and living standards from India’s two-decade-old economic boom, India still has an estimated 626 million people who live in households without toilets.

With a total population of 1.27 billion, this means that nearly half of India’s population practices “open defecation.” According to the World Health Organization (WHO), the practice has dire consequences for health — especially for the healthy development of children.

When people defecate in fields and other places where poor children also play, the children are inadvertently exposed to parasites and bacteria that lead to physical and cognitive development problems and higher mortality rates. These in turn jeopardize the country’s future economic potential.

B. India’s Muslims are less affected by the sanitation problem than Hindus is true.

India consists of two major ethnic groups — Hindus, who make up about 80% of the population, and Muslims, who account for about 15%. For centuries, Hindus have been encouraged to defecate in the open, far from their homes, in order to maintain ritual purity.

India’s Muslims, on the other hand, are less likely to view in-house latrines as “impure.” Thus, Hindu households are far more likely than Muslim households to engage in the practice of open defecation.

Children are especially susceptible to the fecal pathogens the practice spreads. According to several academic and government studies, open defecation is the primary explanation for the higher mortality rate for Hindu children than Muslim children. Experts would ordinarily expect the opposite — given Hindus’ higher average incomes and educational attainment than Muslims.

C. India’s lack of toilets is worse than China’s is true.

An estimated 1.1 billion people — about 15% of the world population — practice open defecation, according to WHO data for 2010. They may do so because of cultural norms (as in the case of India’s Hindus) or because of a simple lack of indoor toilets.

In China — the only nation other than India with a population over one billion — a comparatively small number of people still practice open defecation. The number of Chinese who practice open defecation (14 million) is 45 times smaller than the number of Indians who do so (626 million).

Since 1990, 593 million Chinese and 251 million Indians have gained access to improved sanitation, according to WHO estimates. However, water sources befouled by human waste (as well as by agricultural waste and industrial effluents) continue to pose significant health risks in both countries.

An estimated 75% of India’s surface water is contaminated and unfit for human consumption. The estimated 97 million Indians who lack access to improved drinking water are second, as a group, only to the 119 million Chinese.

D. Lack of toilets in India puts women at especially high risk is true.

In 1925, when India’s independence was still more than two decades away, Mohandas Gandhi famously said, “Sanitation is more important than independence.” India’s newly elected prime minister, Narendra Modi, invoked that statement on the campaign trail when he declared, “Sanitation is more important than temples.”

Modi’s administration has announced plans to invest in public sanitation projects throughout what will soon be the world’s most populous country and to build thousands of public toilets. His goal is to eliminate open defection in India by 2019, the 150th anniversary of Gandhi’s birth.

Ending the practice will also help eliminate a dire public safety problem for women. In May 2014, two teenage girls were raped and killed while visiting a field used as a communal toilet — and many similar attacks on girls and women have been documented.

Because 130 million of India’s households lack toilets, women and girls often have no other option than to venture out — often at night and alone — to relieve themselves.