This is a Sufficient Assumption question. We're looking for the sufficient assumption--the one that fills the gap and makes the argument work.
The core is:
The center can't operate on less than 2.5 mil
+
The budget for this year is 1.5 mil
-->
There's no way the center can keep running
What if the center can get money from other sources though? (C) tells us this is not the case. It makes the argument work.
(A) is counter to the argument. If the center didn't use the $4 mil, maybe it can use it this year.
(B) is irrelevant.
(D) is also irrelevant because the center could perhaps still get funding from another source besides other programs.
(E) doesn't matter. What they value isn't about how much money will be available.