Astronomy current events question: R Sculptoris spiral structure

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!)

Matthias Maercker, Wouter Vlemmings Onsala Space Observatory, Shazrene S. Mohamed, and Douglas Pierce-Price, "Surprising Spiral Structure Spotted by ALMA," October 10, 2012
http://www.eso.org/public/news/eso1239/

The Atacama Large Millimeter/submillimeter Array (ALMA) has discovered a spiral structure in the gas surrounding the star R Sculptoris, which European Southern Observatory scientists speculate may be caused by:
(A) the star's core suddenly collapsing.
(B) gravitational lensing.
(C) a central supermassive black hole.
(D) a hidden companion star.
(E) a bubble of dark matter.

Correct answer: (D)

Student responses
Sections 70178, 70186, 70200
(A) : 12 students
(B) : 7 students
(C) : 2 students
(D) : 26 students
(E) : 4 students