Astronomy current events question: Mars' buried carbon dioxide

Astronomy 210L, Spring 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!)

Guy Webster, Maria Martinez, Dwayne Brown, "NASA Orbiter Reveals Big Changes in Mars' Atmosphere," April 21, 2011
http://www.nasa.gov/mission_pages/MRO/news/mro20110421.html

Ground-penetrating radar from NASA's Mars Reconnaissance Orbiter has detected:
(A) large buried deposits of frozen carbon dioxide.
(B) underground reservoirs of liquid water.
(C) warm magma pockets under Olympus Mons.
(D) a network of long, straight underground tubes.
(E) remnants of a large asteroid impact.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 14 students
(B) : 3 students
(C) : 0 students
(D) : 1 student
(E) : 3 students