Even though there is not pronoun in bold, we can assume this question refers to "himself" because of the options given.
Answer:
The pronoun in bold in the sentence is:
D. reflexive.
Explanation:
There are two pronouns in the sentence we are analyzing here: "himself" and "his". "His" is a possessive pronoun and, since that is not one of the options, we can leave it aside. Let's focus on "himself", which is a reflexive pronoun. A reflexive pronoun, as the name suggests, usually reflects the action back to the subject of the sentence. However, when used with "by", it indicates the action was performed by that person alone. That is the case here. The speaker is saying his father went to Colorado alone when he uses "by himself".
