执行下面python代码后,输出的结果是?
def add(c): d = c.append(40) return d a = [10, 20, 30] b = add(a) print(a, b)
[10, 20, 30] [10, 20, 30]
[10, 20, 30, 40] [10, 20, 30, 40]
[10, 20, 30] [10, 20, 30, 40]
[10, 20, 30, 40] None