Astronomy current events question: subsurface ice on Vesta?

Astronomy 210L, spring semester 2012
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 and Jia-Rui Cook, "Vesta Likely Cold and Dark Enough for Ice," January 25, 2012
http://www.nasa.gov/mission_pages/dawn/news/dawn20120125.html

The asteroid Vesta may contain ice just below its surface, according to models based on:
(A) Antarctic glaciers.
(B) a Russian space probe drilling into its crust.
(C) meteorite samples containing Vesta material.
(D) Hubble Space Telescope observations.
(E) icy vapor trails.

Correct answer: (D)

Student responses
Sections 30678, 30679, 30680
(A) : 4 students
(B) : 2 students
(C) : 7 students
(D) : 15 students
(E) : 0 students