为什么选D不选C __ their students with good social experiences and interpersonal skills,

__ their students with good social experiences and interpersonal skills,universities have become a lot more social than the "Ivory Tower" of the past.
这个只能选D,表示原因.
相当于
Because they equip their students with good ...,
选C表示目的,不能改为
In order that they equip their students with good...
意思是
由于大学让学生获得了社会经历和人际交流技能,因此大学已经成为了更社会化而不是过去的“象牙塔”了.