@Gabe
After reading it like 5 times, I THINK I got it. If I'm wrong please correct me, but this is how my mind is working based on the answer choice being D.
Okay so the risk of incorrect rejection is a substantive risk in which you reject a balance as being free from material misstatement when in fact the balance is free from material misstatement. This leads to audit inefficiency. The cost and effort of selecting an additional sample being low relates to inefficiency because as an auditor you are not looking to expand much cost or effort when doing your substantive test. So because you're not doing as much work, you raise the risk of incorrect rejection, which leads to audit inefficiency, which ALSO raises detection risk.
Okay I might've confused myself with my own explantation lol. That's a good ass question! Where'd you get it from?
FAR - (Let's not talk about that score)
AUD - 77!
REG - 70, 70
BEC - 77!