Astronomy current events question: shrinking moon

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, "Lunar Reconnaissance Orbiter Reveals Incredible Shrinking Moon," August 20, 2010
http://www.astronomy.com/asy/default.aspx?c=a&id=10155

NASA's Lunar Reconnaissance Orbiter recently observed __________, which may indicate that the moon shrank recently, and may still be shrinking today.
(A) sizes of craters decreasing over time.
(B) fresh lava flows.
(C) mud volcanoes.
(D) cliffs that cut across small craters.
(E) growing sinkholes.

Correct answer: (A)

Student responses
Sections 70178, 70186, 70200
(A) : 5 students
(B) : 0 students
(C) : 0 students
(D) : 27 students
(E) : 2 students