Astronomy current events question: Pan's equatorial ridge

Astronomy 210L, spring semester 2017
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!)

Tony Greicius, "Pan Revealed" (March 16, 2017)
nasa.gov/image-feature/jpl/pia21436/pan-revealed

The thin ridge around the equator of Saturn's moon, Pan, imaged by NASA's Cassini spacecraft may have been formed from material:
(A) gathered from Saturn's rings.
(B) flattened between two colliding smaller moons.
(C) flung out during rapid rotation.
(D) ejected from ice geysers.
(E) from moonquake faults.

Correct answer: (A)

Student responses
Sections 30679, 30680
(A) : 13 students
(B) : 4 students
(C) : 8 students
(D) : 3 students
(E) : 1 student