GMAT 语法149.Recently there has been increased debate over if

GMAT 语法
149.Recently there has been increased debate over if a budget surplus should go towards lower taxes or increased spending on social programs.
(A) over if a budget surplus should go towards lower taxes or increased spending
(B) over whether a budget surplus should go towards lowering taxes or increasing spending
(C) about a budget surplus going towards lower taxes or increasing spending
(D) about if lower taxes should come from a budget surplus or spending increases
(E) concerning a budget surplus and its going towards lower taxes or increased spending
答案说是B,但我觉得是E,B不是应该用or not 的么?