سوال ۱ کنکور ارشد علوم کامپیوتر ۱۴۰۰

The sentence needs a verb meaning that the eyewitness confirmed/supported the speaker's account, which is why the police then believed it.

corroborate = to confirm or give support to a statement, theory, or finding with additional evidence. It collocates exactly with this context: an eyewitness corroborated my account. This is the answer — option (3).

Why the others fail:

• display = to show or exhibit something — you display feelings or objects, not someone else's account.
• constitute = to make up or form a whole; it does not mean to confirm a statement.
• suspect = to believe something (often bad) is true without proof, or to doubt — the opposite of confirming, and it would not lead the police to believe the speaker.

Exam trick: The causal link "police only believed me after ..." signals the blank verb must mean confirm/back up. Corroborate is the standard collocation with evidence/testimony/account.