Engagement Letter (EL)

Dear Sir,

I have worked an MCA question from Kaplan Publishing which is as follows:

Which of the following does not need to be performed prior accepting a new client?
A – Money Laundering checks
B – Consideration of Ethical Issues
C – Obtain professional clearance from the outgoing auditor
D – Signing the Engagement Letter

All the answers seem correct to me. But the answer as per Kaplan is D.
I am confused as I believe that an EL should be signed prior accepting the new client as this letter not only describes the auditor’s responsibilities but also the management’s responsibilities.

Grateful if you could assist.