Astronomy current events question: flowing water on Mars

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!)

Guy Webster, Steve Cole, and Daniel Stolte, "NASA Spacecraft Data Suggest Water Flowing on Mars," August 4, 2011
http://www.jpl.nasa.gov/news/news.cfm?release=2011-242

__________ observed by NASA's Mars Reconnaissance Orbiter may be evidence of salt water flowing on Mars.
(A) Shifting positions of boulders and other rock debris.
(B) Wearing down of angular rock formations.
(C) Light reflected by rocks exposed by meteor impacts.
(D) The appearance and disappearance of dark rivulets.
(E) Accumulation of ice in shadowed north and south pole craters.

Correct answer: (D)

Student responses
Sections 70178, 70186, 70200
(A) : 1 student
(B) : 9 students
(C) : 2 students
(D) : 15 students
(E) : 1 student