어법상 옳지 않은 것은?


Princeton University offers a tuition-free, nine-month
“Bridge Year” in which students can elect ① to do a
service project outside of the U.S. The University of
North Carolina at Chapel Hill and Tufts University have
similar programs, while ② ones run by the New School
in New York City offers up to a year’s worth of
academic credit to participants. But in the last five years,
the idea has been ③ gaining more traction in the U.S.―
particularly among Americans ④ admitted to selective
colleges and universities.