for the reason that/why

题目

for the reason that/why
Once i was a soldier.While in the army there was nothing that i disliked so much as the map-reading course,for the reason____i always felt lost even with amap in my hand..
完型的第一道题 ...不懂
a.which
b.why
c.for which
d.that.
选什么为什么

答案

that ,that 后的句子作定语从句修饰reason ,for …表原因