Read the lines from An Essay on Man.

In doubt to deem himself a god, or beast;

In doubt his mind or body to prefer;

Which element is used in these lines?

repetition

rhyme

free verse

heroic couplet

The correct answer is repetition.

Repetition can be seen by the usage of the phrase "in doubt" to start both lines in order to emphasize the state the speaker describes and set the tone of the poem.

repetition

Explanation:

Repetition is a literary device that consists of repeating words or lines in a stanza. In this case, the author repeats "In doubt", which is used to reinforce this idea of being uncertain. The deliberate repetition of the first part of a sentence with the goal being to achieve an artistic effect is what we call an Anaphora, which is the case in the lines presented.