Astronomy current events question: twin GRAIL spacecraft crashes

Astronomy 210L, spring semester 2013
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!)

Nancy Neal-Jones and Bill Steigerwald, "NASA's LRO Sees GRAIL's Explosive Farewell," March 19, 2013
http://www.nasa.gov/mission_pages/LRO/news/grail-results.html

NASA's twin Gravity Recovery and Interior Laboratory spacecraft crashed into the moon's north pole regions in order to __________, as observed by the Lunar Reconnaissance Orbiter.
(A) kick up dust and gas plumes.
(B) avoid disturbing the Apollo landing sites.
(C) create future moon base shelters.
(D) measure the moon's gravitational pull.
(E) release raw building blocks of life.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 38 students
(B) : 3 students
(C) : 1 student
(D) : 11 students
(E) : 1 student