1. The creation of the Department of Homeland Security (DHS) was spurred primarily by A the attack on the USS Cole in 2000. B the terror attack in New York in 2001. C the 2001 anthrax letter attacks.
Dthe Clinton administration's "Reinventing Government" project.​

B) the terror attack in New York in 2001.

Explanation:

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.