Among the15-year-old children, some ________ studying in university while others arestill learning t

Among the15-year-old children, some ________ studying in university while others arestill learning to read and write.

A.shouldhave been

B.would havebeen

C.can be

D.must be

答案及解析： C

解析：

can这里表示可能性，指现在。