If X = {1, 2, 3, 4, 5}, Y = {1, 3, 5, 7, 9} determine which of the following relations from X to Y are functions? Give reason for your answer. If it is a function, state its type.
(i) R1 = {(x,y)| y = x + 2, x ∈ X, y ∈ Y}
(ii) R2 = {(1,1), (2,1), (3,3), (4,3), (5,5)}
(iii) R3 = {(1,1), (1,3), (3,5), (3,7), (5,7)}
(iv) R4 = {(1,3), (2,5), (4,7), (5,9), (3,1)}