Givearecursivedefi of positive integers. [ hint: plot the points in the setin the plane and look for lines containing points in theset.] a) s = { (a, b) | a ∈ z + ,b ∈ z + , and a + b is odd } b) s = { (a, b) | a ∈ z + ,b ∈ z + , and a | b } c) s = { (a, b) | a ∈ z + ,b ∈ z + , and 3 | a + b slader