Choose whether to use a colon or a semicolon in this sentence!

I can't decide which I like ______ cats or dogs.

To determine whether to use a colon or a semicolon in the sentence "I can't decide which I like ______ cats or dogs," you need to consider the relationship between the two parts of the sentence.

1. Colon (:) - A colon is used to introduce a list, explanation, or further information that directly follows a complete statement.
- Example: "I can't decide which I like more: cats or dogs."

2. Semicolon (;) - A semicolon is used to join two independent clauses that are closely related to each other.
- Example: "I can't decide which I like more; cats or dogs."

In this case, the sentence does not contain two independent clauses, but rather a complete statement ("I can't decide which I like more") followed by a list of options ("cats or dogs"). Thus, a colon would be the appropriate punctuation mark to use in this sentence.