Astronomy current events question: TRAPPIST-1 planet water content

Astronomy 210L, fall semester 2017
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!)

Vincent Bourrier, Julien de Wit, and Mathias Jäger, "Hubble Delivers First Hints of Possible Water Content of TRAPPIST-1 Planets" (August 31, 2017)
spacetelescope.org/news/heic1713/

Planets orbiting dwarf star TRAPPIST-1 may retain some water, based on Hubble Space Telescope observations of:
(A) reflective ice crystals.
(B) escaping water plumes.
(C) gamma ray emissions.
(D) gravitational wave fluctuations.
(E) absorbed ultraviolet light.

Correct answer: (E)

Student responses
Sections 70178, 70186
(A) : 8 students
(B) : 14 students
(C) : 7 students
(D) : 2 students
(E) : 15 students