Astronomy current events question: MESSENGER orbiting Mercury

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!)

Mike Wall, "NASA Probe Becomes First Spacecraft to Orbit Mercury," March 17, 2011
http://www.space.com/11160-nasa-spacecraft-mercury-orbit-messenger.html

On March 17, NASA's Messenger spacecraft fired its main thruster in order to:
(A) catch up to dock with a fueling station.
(B) slow down to begin orbiting Mercury.
(C) avoid collision with an asteroid.
(D) boost its orbit away from a solar flare.
(E) reach the opposite side of the sun.

Correct answer: (B)

Student responses
Sections 30678, 30679, 30680
(A) : 0 students
(B) : 37 students
(C) : 5 students
(D) : 5 students
(E) : 2 students