Astronomy current events question: Phobos' surface egrooves

Astronomy 210L, fall 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!)

Elizabeth Zubritsky, "Mars’ Moon Phobos is Slowly Falling Apart" (November 10, 2015)
nasa.gov/feature/goddard/phobos-is-falling-apart

Computer models indicate that the grooves on Mars' moon Phobos may be produced by:
(A) solar heating.
(B) convection currents.
(C) cryovolcanoes.
(D) Mars' gravity.
(E) its rapid rotation.

Correct answer: (D)

Student responses
Sections 70178, 70186
(A) : 1 student
(B) : 3 students
(C) : 1 student
(D) : 15 students
(E) : 0 students