Answer:
The topic that best relates to the central idea in this part of the speech is "Keeping the nation safe". The excerpt discusses the ongoing threat posed by Al-Qaida and other terrorist networks, as well as the danger of the proliferation of deadly weapons. The central idea is that the United States government is committed to defending the nation and taking measures to hunt down the enemy before they can strike. Therefore, the correct answer is A) Keeping the nation safe.