A. Wolfson, Elijah. “Newsweek Names a Mars Crater.” Newsweek. Newsweek, 28 Feb. 2014. Web. 1 Mar. 2014.
B. Herman, Barbara. “Where’s the Fire?” Newsweek. Newsweek, 24 Oct. 2013. Web. 25 Feb. 2014.
D. “A Mighty Girl.” N.p., n.d. Web. 26 Feb. 2014.
Answer:
I believe the one you selected (B) is correct.
Explanation:
It shows how long it took to easily kindle a fire and how hard this was.
A clause is a group of related words with a subject and verb.