The answer is B, or I e wasn’t sure why he was angry. His mood came out of left field.
Explanation:
An idiom is a phrase that is not meant to be taken literally because it adds emphasis to another event. In B, an example of an idiom is shown because the person’s mood does not literally come out of left field. The sentence makes a reference to baseball, and because a mood cannot physically come out of left field, this sentence is not meant to be taken verbatim. The other sentences provided are actual sentences which straightforwardly exert an idea or claim. Therefore, B is an example of an idiom.
