Astronomy current events question: habitability of watery exoplanets?

Astronomy 210L, fall semester 2018
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!)

Louise Lerner, "Water Worlds Could Support Life, Study Says" (August 31, 2018)
news.uchicago.edu/story/water-worlds-could-support-life-study-says

Based on computer simulations, exoplanets with deep oceans may be habitable if __________ can be cycled between their atmospheres and oceans.
(A) amino acids.
(B) volcanic minerals.
(C) carbon.
(D) chlorophyll.
(E) sulfur chains.

Correct answer: (C)

Student responses
Sections 70178, 70186
(A) : 3 students
(B) : 3 students
(C) : 18 students
(D) : 0 students
(E) : 1 student