Astronomy current events question: Andromeda Galaxy stellar populations

Astronomy 210L, spring semester 2015
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!)

Tim Stephens, "Study of Andromeda's Stellar Disk Indicates More Violent History than Milky Way," (January 8, 2015)
http://news.ucsc.edu/2015/01/andromeda-galaxy.html

The Andromeda galaxy may have merged with several smaller galaxies in the past, based on analyzing data from the Keck Observatory and Hubble Space Telescope of its:
(A) central supermassive black hole.
(B) look-back time.
(C) dark matter halo.
(D) gravitational pull.
(E) star velocities and ages.

Correct answer: (E)

Student responses
Sections 30678, 30679, 30680
(A) : 5 students
(B) : 3 students
(C) : 4 students
(D) : 14 students
(E) : 34 students