Answer:
3. He should encourage audience participation by asking questions or requesting examples.
Explanation:
When an audience is not engaged in a speech it means that they are not interested in the contents of the speech or rather the way contents have been presented.
The purpose of a speech is to impart knowledge to a large group of people if the audience is not interested in the speech then the main function of a speech is not fulfilled. The speaker should not ignore the speech or provide additional data but instead, encourage the audience to participate. This would involve the audience in the speech.
Hence the answer is 3. He should encourage audience participation by asking questions or requesting examples.