Astronomy current events question: Mercury's polar ice

Astronomy 210L, fall 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!)

NASA press release, "MESSENGER Finds New Evidence for Water Ice at Mercury's Poles," November 29, 2012
http://www.nasa.gov/mission_pages/messenger/media/PressConf20121129.html

NASA's MESSENGER spacecraft was able to confirm the presence of Mercury's __________ using three different types of measurements.
(A) warm molten core.
(B) plate tectonics.
(C) hydrocarbon lakes.
(D) polar water ice.
(E) dormant volcanoes.

Correct answer: (D)

Student responses
Sections 70178, 70186, 70200
(A) : 5 students
(B) : 1 student
(C) : 2 students
(D) : 20 students
(E) : 6 students