i want to say its (C) but it might also be (B)
I believe 3b/6a which could reduce to b/3a.
I forgot how to do this sorry
Answer:
here
Step-by-step explanation:
https://www.rcboe.org/cms/lib/GA01903614/Centricity/Domain/1351/21.2%20permutations%20and%20probability.pdf