Click on the box to choose whether the sentence is correct (c), contains a comma splice (cs), or is a fused sentence (fs). i realized that i had forgotten my coat and left my hat hanging in the closet.

The sentence is correct. It does not contain a CS because it does not have any comma joining two independent clauses. It is not a FS because the two independent clauses here are joined by a connecting word between them, and a FS does not have any punctuation or connecting word between the two independent clauses. The result is that the sentence is correct because there are two independent clauses joined by a connecting word, which is "and."