Astronomy current events question: observing effects of C/2013 A1 (Siding Spring) on Mars' atmosphere

Astronomy 210L, fall semester 2014
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!)

APPEL news staff, "A Rare Event Offers Insight into Solar System Origins," (November 24, 2014)
http://appel.nasa.gov/2014/11/24/a-rare-event-offers-insight-into-solar-system-origins/

NASA and European Space Agency spacecraft are measuring the effects on Mars' atmosphere due to dust deposited by a:
(A) reactivated volcano.
(B) nearby comet.
(C) small asteroid impact.
(D) planet-wide sandstorm.
(E) solar flare.

Correct answer: (B)

Student responses
Sections 70178, 70186
(A) : 5 students
(B) : 29 students
(C) : 1 student
(D) : 2 students
(E) : 0 students