In each of the following questions, choose the option that best completes the gap(s). He presented a masterpiece at the conference, ___________

This question tests question tags. The rule is: identify the auxiliary verb in the main clause, then form a short tag question using the same auxiliary in the opposite polarity (positive statement gets a negative tag).

The main clause is "He presented a masterpiece at the conference." The verb presented is in the simple past tense and is a regular action verb with no visible auxiliary. When the main verb is in the simple past without an auxiliary, the tag is formed using did.

Since the statement is positive ("He presented..."), the tag must be negative: didn't he?

The other options are wrong:

• was he? and wasn't he? use the auxiliary "was," which would only be correct if the main clause used the past continuous ("He was presenting...") or the passive voice ("A masterpiece was presented..."). Neither applies here.
• did he? has the correct auxiliary but the wrong polarity - a positive statement requires a negative tag, not another positive one.