Astronomy current events question: Milky Way disk bubbles

Astronomy 210L, spring 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!)

NASA/Jet Propulsion Laboratory press release, "Citizen Scientists Reveal a Bubbly Milky Way," March 7, 2012
http://www.spitzer.caltech.edu/news/1386-feature12-03-Citizen-Scientists-Reveal-a-Bubbly-Milky-Way

New "bubbles" created by hot, young stars in the disk of the Milky Way galaxy were discovered from NASA's Spitzer Space Telescope data by:
(A) recolorizing black and white infrared images.
(B) comparing old images from NASA's Hubble Space Telescope.
(C) asking internet volunteers to count bubbles.
(D) blocking out gamma radiation from the supermassive central black hole.
(E) using interferometry together with ground-based telescopes.

Correct answer: (C)

Student responses
Sections 30678, 30679, 30680
(A) : 8 students
(B) : 9 students
(C) : 22 students
(D) : 9 students
(E) : 6 students