Astronomy current events question: Saturn's warmer than expected "A" ring

Astronomy 210L, fall 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!)

Preston Dyches, "At Saturn, One of These Rings Is Not Like the Others" (September 2, 2015)
jpl.nasa.gov/news/news.php?feature=4709

Comparison of computer__________ models with data taken by NASA's Cassini spacecraft may explain the warmer than expected temperatures of Saturn's "A" ring.
(A) convection current.
(B) particle composition.
(C) magnetic field.
(D) gravitational.
(E) greenhouse effect.

Correct answer: (B)

Student responses
Sections 70178, 70186
(A) : 2 students
(B) : 20 students
(C) : 3 students
(D) : 2 student
(E) : 3 students