Astronomy current events question: Saturn "rain"

Astronomy 210L, fall semester 2011
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!)

Denise Chow, "Aha! Icy Moon 'Rain' Creates the Water on Saturn," July 27, 2011
http://www.msnbc.msn.com/id/43912513/ns/technology_and_science-space/

According to observations from the ESA Herschel Space Observatory, water raining down on Saturn may come from:
(A) icy geysers on its moon, Enceladus.
(B) comet fragments.
(C) intense lightning storms in its atmosphere.
(D) its greenhouse effect.
(E) the disrupted formation of a small icy moon.

Correct answer: (A)

Student responses
Sections 70178, 70186, 70200
(A) : 23 students
(B) : 2 students
(C) : 2 students
(D) : 3 students
(E) : 1 student