Astronomy current events question: potentially habitable planets start as "mini-Neptunes?"

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!)

Peter Kelley, "Some Potentially Habitable Planets Began as Gaseous, Neptune-like Worlds," (January 28, 2015)
http://www.washington.edu/news/2015/01/28/some-potentially-habitable-planets-began-as-gaseous-neptune-like-worlds/

Researchers propose that potentially habitable planets may begin as gaseous, Neptune-like worlds based on:
(A) computer simulations.
(B) planets passing in front of their stars.
(C) gravity wave measurements.
(D) observations of transferred gases.
(E) disappearing gas giants.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 9 students
(B) : 6 students
(C) : 11 students
(D) : 18 students
(E) : 7 students