Consider the two sets A = {n EN:n is both a perfect square and a perfect cube}and B = {r € N:r = 0mod 7 or r = 1mod 7). If one wishes to prove A = B. then which of thefollowing describes a valid proof strategy? Select only one answer.(a) Suppose z € A and prove r e B, and then suppose r&A and show r & B.(b) Suppose z E A and prove z € B.(c) Suppose z € An B and conclude re AUB.(d) Suppose z € B and conclude z E A. and then suppose z E A and conclude a contradiction.(e) Suppose z B and conclude z € A.