Select the most appropriate ANTONYM of the highlighted word.

Let’s ascertain whether his claims have any truth.

disprove

The most appropriate antonym of the highlighted word ascertain is disprove.

• Ascertain means "to find out for sure or to establish the truth of something."
• Disprove means "to show that something is not true."

The other words do not have the same meaning as ascertain, so they are not its antonyms.

• Detect means "to find or discover something that is hidden or not obvious."
• Approve means "to give one's consent or approval to something."
• Prove means "to show that something is true by providing evidence."