一道英语选择,说下选哪个,并说明理由

问题描述:

一道英语选择,说下选哪个,并说明理由
The survey found that young people would improve their job prospects _______ they studied business studies,maths,English and physics or chemistry at A-level.
A until B since C whereas D if

D.if 如果(引导条件状语从句)
句意:调查发现,如果年轻人学习了商业研究,数学,英语及物理或化学并达到A级,
他们就会提升自己的就业前景.
(until 直到 since自...以来 whereas 然而,反之 )这三个都不合适.