P(A) = probability of event A, P(B) = probability of event B
P(A) = x is given to us
P(B) = y is also given
--------------------------
If A and B are independent, then neither event affects the other. If we know A happens, then that doesn't change the probability of B happening (vice versa).
So that means P(A|B) = P(A) = x and P(B|A) = P(B) = y
This points to the answer being P(B|A) = y which is choice A or the first answer choice
note: P(A|B) is read as "probability of A given that B has happened". It is known as conditional probability. The symbol between the A and B is not the letter i or L, it is a vertical pipe symbol to separate the letters.