Americans are said to be sleep-deprived people, and teenagers are the worst of the lot. Many live in a state of chronic sleep deficit that can affect mood, behavior!, school work, and reaction time. Physical, emotional and social factors seem to conspire against letting adolescents get enough sleep. When teenagers insist that they are not tired at 9 or 10 p.m., they are very likely to ______. For reasons that are not fully understood, their body clocks shift, so that their natural tendency is to stay up later at night and wake up later in the morning than when they were younger. But that inner clock often clashes with the outer world.

(a) be very negative
(b) be selling the truth
(c) be eager to stay late
(d) be wanting to party all night

이게 답이 b라는데요 왜 c는 안되나요? 그리고 sell the truth는 뜻이 진실을 왜곡하다 머

이런뜻을 가지고 있나요? 부탁드려요