The external auditors testing of internal controls typically represent a major component of the audit. Every audit client is different, as are the industries they operate in$,$ which affects the auditors' assessment of the client's system of internal control. Which of the following is correct with respect to the external auditor's testing of internal control?

The external auditors often adopt a reliance strategy whereby control risk is assessed as high and then auditors adopt increased substantive procedures.

Generally accepted auditing standards require that in most circumstances, the external auditors defer internal control testing to the internal audit function.

The external auditors typically attempt to gain an understanding of the client, and then test all controls in order to be able to issue a clean opinion on internal control.

The external auditors typically determine where internal control weaknesses may be by gaining an understanding of the client and then testing selected controls.