Answer:
The answer is D, Winston Churchill addressed the House of Commons with these famous words:
Step-by-step explanation:
It fits the sentence best, by using process of elimination we can find the answer.
A wouldn't fit because it starts with although, so the other half would say something that would introduce information, but it doesn't.
B doesn't fit because it would offer a explanation, which it does not.
C doesn't fit because if it talks about a speech, and the other clause isn't a speech, it's famous words.
D fits because it says famous words, and the other half is a part of a speech which Churchill spoke.
I tried my best to explain it, i hope it's correct! Good luck with your studies.