Fill in the blank with the most appropriate word.I'll ask him what he ___ for lunch.

Answer: Option A

The sentence requires a verb tense that matches the context of a past action.

"Was having" is in the past continuous tense, which is used to describe an action that was happening at a particular time in the past.

In this case, "I'll ask him what he was having for lunch" correctly conveys that the speaker intends to inquire about what the person was eating during a past moment.