Which of the following statements about Python expressions is true (choose all that apply). O a. To negate a value of a variable you use the (--) operator. b. In Python operators such (--) and (= b: return a else: return b Which of the following is an incorrect way of using the function ay max? . X = 10 y = 15 my_max(x, y) O b. d = [8, -16, 32, 64] my_max(d[-1], my_max(72, d[3])) Oc my_max(my_max(1, 2), my_max(-20, 4)) O d. my_max(5, 6, -7)