单选题：选择下面程序的运行结果

选择下面程序的运行结果@[D](2)

x,y,z=1,-1,1
if x > 0:
if y > 0:
print("x > 0 and y > 0")
elif z > 0:
print("x < 0 and z > 0")


A. x > 0 and y > 0
B. x < 0 and z > 0
C. x < 0 and z < 0
D. nothing displayed




A.x > 0 and y > 0
B.x < 0 and z > 0
C.x < 0 and z < 0
D.nothing displayed


答案：D