Last week, Facebook COO Sheryl Sandberg told CNBC that while the company currently allows users to opt out of certain features, "We don't have an opt-out at the highest level. That would be a paid product." Hatch asked about those comments and Zuckerberg reiterated that ads are a major part of how Facebook sustains its business. It's interesting to now hear Zuckerberg say that a version of Facebook will always remain free.

Zuckerberg's testimony is ongoing, you can follow along here.