Under a single audit:

Option A

An audit must be performed encompassing the nonfederal entity$$s financial statements and schedule of expenditures of federal awards.

Option B

The audit must be conducted by an independent auditor in accordance with generally accepted government auditing standards $($GAGAS$)$ and cover the operations of the entire nonfederal entity.

Option C

For each major program, the auditor must obtain an understanding of the internal controls pertaining to the compliance requirements for the program, assess control risk, and perform tests of controls, unless the controls are deemed to be ineffective.

Option D

All of the given statements regarding a single audit are true.