OG第一题有一处不明

1、 The Wallerstein study indicates that even after a decade young men and women still experience some of the effects of a divorce occurring when a child.

(A) occurring when a child

(B) occurring when children

(C) that occurred when a child

(D) that occurred when they were children（D）

(E) that has occurred as each was a child

OG给的答案里说E选项错误地将when换成as（E里面其它的错误明白了，但就这个不理解）。