Which sentence has a pronoun with an unclear, missing, or confusing antecedent?

A.

After I read the book, I returned it to the library.

B.

I found a caterpillar on a leaf, and I carefully carried it to my brother.

C.

This shirt is dirty, so I will put it in the laundry basket.

I believe it would be B, because there are two subjects that the speaker is referring to at the beginning of the sentence; the caterpillar and the leaf. When they use the word "it" in the second half of the sentence it is unclear whether they mean to say if "it" is the leaf or the caterpillar which they are carrying to their brother.