Astronomy current events question: "galactic murder mystery"

Astronomy 210L, spring semester 2017
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!)

Toby Brown, Barbara Catinella, and Pete Wheeler, "Galactic Murder Mystery" (January 17, 2017)
icrar.org/galaxy-murder-mystery/

A study of 11,000 galaxies shows that their star-forming gases are being stripped away as they pass through ___________ surrounding larger galaxies.
(A) primordial matter.
(B) dark matter halos.
(C) clumps of antimatter.
(D) cosmic background radiation.
(E) bipolar gas jets.

Correct answer: (B)

Student responses
Sections 30679, 30680
(A) : 2 students
(B) : 24 students
(C) : 3 students
(D) : 2 students
(E) : 0 students