Astronomy current events question: dust transport on comet 67P/Churyumov–Gerasimenko

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!)

European Space Agency news release, "Getting to Know Rosetta's Comet," (January 22, 2015)
http://www.esa.int/Our_Activities/Space_Science/Rosetta/Getting_to_know_Rosetta_s_comet

Observations of the surface of comet 67P/Churyumov–Gerasimenko by the European Space Agency may be evidence of dust transported across its surface by:
(A) avalanches.
(B) flowing water.
(C) escaping gases.
(D) solar winds.
(E) asteroid impacts.

Correct answer: (C)

Student responses
Sections 30678, 30679, 30680
(A) : 2 students
(B) : 9 students
(C) : 28 students
(D) : 19 students
(E) : 7 students