单选题：下列程序运行输出结果为_______。

下列程序运行输出结果为_______。 @[](4)

words=['cat','window', 'defenestrate']
for w in words[:]:
if len(w)>6:
words.append(w)
print(words)

A. ['defenestrate']
B. ['window', 'defenestrate']
C. ['cat', 'window', 'defenestrate']
D. ['cat', 'window', 'defenestrate', 'defenestrate']

答案：D