Astronomy current events question: Large and Small Magellanic Cloud edges

Astronomy 210L, spring semester 2015
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)

David Lee Nidever and Knut Olsen, "NOAO: Smashing Results About Our Nearby Galactic Neighbors," (January 5, 2015)
http://www.noao.edu/news/2015/pr1501.php

The non-uniform edges of the Large and Small Magellanic Clouds observed by the Cerro Tololo Inter-American Observatory (CTIO) in Chile may be debris from:
(A) cosmic background radiation.
(B) supernova remnants.
(C) past interactions.
(D) black hole accretion disks.
(E) dark matter.

Correct answer: (C)

Student responses
Sections 30678, 30679, 30680
(A) : 12 students
(B) : 15 students
(C) : 21 students
(D) : 10 students
(E) : 3 students