Fox Business Network/screengrab
Maria Bartiromo, center, and the two other moderators.
Near the end of the debate, Bartiromo was interrupted when she asked the candidates to compare their records against Clinton. Bartiromo said Clinton has an "impressive résumé," provoking the audience reaction.
The moderator pointed out that Clinton has spent "more time in government than almost all of you on stage tonight."
"Why should the American people trust you to lead this country even though she has been so much closer to the office?" she asked.
Sen. Marco Rubio (R-Florida) fielded the question first and praised the inquiry despite the booing.
"That's a great question and let me begin by answering it," he said to laughs. "This election is actually a generational choice, a choice about what kind of nation we will be in the 21st century."