Astronomy current events question: x-ray flares from Milky Way's central supermassive black hole

Astronomy 210L, fall semester 2012
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!)

Monica Young, "The Flares from Milky Way’s Black Hole," October 24, 2012
http://www.skyandtelescope.com/news/The-Flares-at-the-Milky-Ways-Center-175598581.html

NASA's Nuclear Spectroscopic Telescope (NuSTAR) has observed x-ray flares which may be produced by __________ the Milky Way's central supermassive black hole.
(A) matter-antimatter reactions within.
(B) hot gases surrounding.
(C) energetic pulsar beams in.
(D) dark energy exiting out of.
(E) interactions of a dwarf black hole with.

Correct answer: (B)

Student responses
Sections 70178, 70186, 70200
(A) : 8 students
(B) : 21 students
(C) : 13 students
(D) : 4 students
(E) : 4 students