Astronomy current events question: gaps in TW Hydrae's protoplanetary disk

Astronomy 210L, spring semester 2016
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!)

Valeria Foncea
, Charles E. Blue, Richard Hook, and Masaaki Hiramatsu
, "ALMA's Best Image of a Protoplanetary Disk" (March 30, 2016)
http://www.almaobservatory.org/en/press-room/press-releases/937-almas-best-image-yet-of-a-protoplanetary-disk

The Atacama Large Millimeter/submillimeter Array's images of rings and gaps in the disk surrounding the sun-like star TW Hydrae may be:
(A) the formation of planets.
(B) supernova shockwaves.
(C) due to gravitational waves.
(D) intermittent stellar winds.
(E) a passing black hole.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 28 students
(B) : 4 students
(C) : 5 students
(D) : 2 students
(E) : 1 student