Astronomy current events question: lunar bombardment

Astronomy 210L, Fall Semester 2010
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!)

Astronomy.com editors, "NASA's LRO Exposes the Moon's Complex, Turbulent Youth," September 17, 2010
http://www.astronomy.com/asy/default.aspx?c=a&id=10237

What recent data from the NASA Lunar Reconnaissance Orbiter spacecraft may provide evidence that the moon was bombarded by two distinct populations of asteroids or comets in the past?
(A) Infrared maps of different composition regions.
(B) Chemical tests of soil sample scrapings.
(C) Orbits of small rocky and icy fragments around the moon.
(D) Discovery of new ice-filled craters at the north and south poles.
(E) Detection of gravitational field anomalies.

Correct answer: (A)

Student responses
Sections 70178, 70186, 70200
(A) : 20 students
(B) : 5 students
(C) : 2 students
(D) : 2 students
(E) : 0 students