Astronomy current events question: Phobos' origin

Astronomy 210L, Fall Semester 2010
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!)

Kelly Beatty, "Phobos: A Chip Off of Mars?," September 21, 2010
http://www.skyandtelescope.com/news/103436939.html

Observations of Phobos' _________ by the European Space Agency Mars Express Orbiter may provide evidence that Mars' moon Phobos was debris blasted off of the surface of Mars.
(A) mineral composition.
(B) crater density.
(C) overall shape.
(D) lava formations.
(E) dry ice in shadowed craters.

Correct answer: (A)

Student responses
Sections 70178, 70186, 70200
(A) : 43 students
(B) : 15 students
(C) : 4 students
(D) : 2 students
(E) : 0 students