Answer
b) None of R,S,T are functions
Work Step by Step
b) For any y ϵ B, there is no (4,y) ϵ R. Hence R is not a function.
(5,5) ϵ S and (5,7) ϵ S , but 5$\ne$7. Hence S is also not a function.
For any y ϵ B, there is no (5,y) ϵ T, also (6,5) ϵ T and (6,6) ϵ T but 5 $\ne$6. Hence T is also not a function
