Which of the following contracts has the MOST risk for the buyer?

thanks for the invitations , the options are not provided

In my opinion

The Time & Materials (T&M) contract is the riskiest one for the buyer, because if the project costs are much higher than the original estimates, the buyer has to swallow them, while the seller keeps getting paid for the time worked.

Thanks for the invitation.

CPAF - Cost Plus Award Fee type of contract pose most ( cost ) risk to the buyer out of the given options.