In the past few years,My Heart Will Go On was a popular song among young people, _______were often heard singing it at parties.
A.who
B.which
C.they
D.that
A
本题考查一个非限制性定语从句,先行词是young people,在从句中作主语。句意为“过去几年里,《我心永恒》这首歌在年轻人中间很流行,经常听他们(指年轻人)在晚会上唱它”。