Mathias Mousseau Was at a Client's Offices and Was Preparing

Mathias Mousseau was at a client's offices and was preparing his work for the following day. He was considering the risk that a material misstatement due to significant error or fraud could
Occur in the client's financial statements. Which of the three main stages of the audit was he
Performing?

A) planning stage
B) performing stage
C) reporting stage
D) none of the above