运行下列代码，正确的输出结果是？（ ）
def yang(n): if n == 0: return [1] else: return[([0]+yang(n-1))[i]+(yang(n-1)+[0])[i] for i in range(n+1) ] print(yang(4))
[1,4,6,4,1]
[1,5,10,10,5,1]
[1,1,1]
[1,3,3,1]
