The correct indirect form of the given sentence is:

The sports coach asked the class prefect where the children had left their record books.

The other options are incorrect:

• The sports coach asked the class prefect where the children leave their record books. This is incorrect because the tense of the reported speech is in the present tense, but the reporting verb is in the past tense.
• The sports coach asked the class prefect where have the children left their record books. This is incorrect because the auxiliary verb "have" is used incorrectly.
• The sports coach asked the class prefect where the children are leaving their record books. This is incorrect because the reported speech is describing an action that happened in the past, not an action that is happening now.