"No, that's not true," Sutton replied.
Representative Joe Neguse, a Colorado Democrat, focused on Facebook.
He pointed out that not only Facebook is the world's largest social network, but that those ranked third, fourth and sixth – WhatsApp, Facebook Messenger and Instagram – are Facebook properties.
Owning the four of the top six players in a market, Neguse said, and spoke for himself. "We have a word for it," he said. "It's called monopoly."
Earlier in the day, in the hearing about Facebook's crypto competition project, Libra, lawmakers saved David Marcus, a senior executive.
The initiative is far from the first effort of its kind. The most well-known cryptocurrency, Bitcoin, is widely used, and it introduced the idea of digital currencies free of government control.
But the Libra effort has focused on crypto inverters and reinforced the voice of critics who say the technology has little value beyond speculative investments and illegal transactions, such as web-based online sales. Last week, President of the Federal Reserve, Jerome H. Powell, said Libra "serious concerns" for "money laundering, consumer protection and financial stability." Mr Trump and Finance Minister Steven Mnuchin have also criticized Libra and other cryptocurrencies in the past week.