Astronomy current events question: IBEX and interstellar atoms

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!)

Ray Villard and Jane Rigby, "IBEX: Glimpses of the Interstellar Material Beyond our Solar System," January 31, 2012
http://www.nasa.gov/mission_pages/ibex/news/interstellar-difference.html

NASA's Interstellar Boundary Explorer discovered atoms that originated outside our solar system by comparing:
(A) galactic wind directions.
(B) trace amounts of iridium.
(C) cosmic ray intensities.
(D) differences in radioactive decays.
(E) oxygen and neon atom ratios.

Correct answer: (E)

Student responses
Sections 30678, 30679, 30680
(A) : 5 students
(B) : 3 students
(C) : 2 students
(D) : 4 students
(E) : 16 students