Answer:
B. which is free for all full-time faculty is the nonrestrictive clause.
Explanation:
A nonrestrictive clause is defined as words that describes a word's meaning. It is not needed to understand the meaning of a sentence. The fact that the college cafeteria "is free for all full-time faculty" is an extra fact that we don't need to know to understand the purpose of the sentence. It also is usually separated by commas, which this part of the sentence is.
Therefore, B. which is free for all full-time faculty is the nonrestrictive clause.
Hope this helps! :D
