Audit evidence (Kaplan kit OT case)

During the testing of Hemsworth Co’s payables balance, several misstatements were found.

Which of the following is the most appropriate initial response your audit firm should take?

1) Report the matter to the client.

2) Increase the amount of testing.

3) Suggest the audit opinion is modified.

4) Discuss the issue with the audit manager.

Hello tutor!!
Option 2 is right but I choose option 4 which is wrong and is second response.

I have a question why would we increase our amount of testing as initial response ?

And on what account balance or transaction should we increase amount of testing ?
Because we have been tested the payables and in my opinion there is no further need to assess payables.
Thank you!!