Astronomy current events question: Mars' underground glaciers

Astronomy 210L, spring 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!)

Nanna Bjørnholt Karlsson, "Mars Has Belts of Glaciers Consisting of Frozen Water" (April 7, 2015)
https://www.cfa.harvard.edu/news/2015-10

Researchers calculated the thickness of underground ice on Mars, based on NASA's Mars Reconnaissance Orbiter __________ measurements.
(A) temperature.
(B) gas composition.
(C) radar.
(D) infrared image.
(E) drill sampling.

Correct answer: (C)

Student responses
Sections 30678, 30679, 30680
(A) : 7 students
(B) : 4 students
(C) : 26 students
(D) : 12 students
(E) : 4 students