Discrete math: Let R, S, and D be the following relations on A...

[yorkstudent]

Hi, I am a Junior in college struggling though the concept of discrete math. I used to be an engineering major that is used to using numbers in math instead of these letters. I understand the value sets but i am unsure how to combine R of S, R of D and vice versa as well as the inverse functions. This question is from a practice test im taking online



Let R, S, and D be the following relations on A = {1,2,3}:
R = {(1,1), (1,2), (2,3), (3,1), (3,3)}, S = {(1,2), (1,3), (2,1), (3,3)},
D = {(1,1), (2,2), (3,3)}
Find

RoS=? R-1=? S-1=? RoD=? DoS=?

A. {(1,1),(1,2),(1,3),(2,3),(3,2),(3,3)} B. {(1,1),(1,2),(2,3),((3,1),(3,3)} C. {(1,1), (2,1), (3,1), (3,2), (3,3)} D. {(1,2), (1,3), (2,1), (3,3)} E. {(1,2), (2,1), (3,1), (3,3)} F. {(1,2), (2,3), (3,1)}