Astronomy current events question: larger estimate for galaxies in universe

Astronomy 210L, fall 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!)

Ray Villard, Mathias Jäger, and Christopher Conselice, "Hubble Reveals Observable Universe Contains 10 Times More Galaxies Than Previously Thought" (October 13, 2016)
hubblesite.org/newscenter/archive/releases/2016/39/full/

Over 90% of galaxies in the universe have yet to be detected, based on __________ of Hubble Space Telescope images.
(A) false-coloring.
(B) lookback times.
(C) 3-D modeling.
(D) dark matter densities.
(E) infrared filtering.

Correct answer: (C)

Student responses
Sections 70178, 70186
(A) : 5 students
(B) : 3 students
(C) : 5 students
(D) : 3 students
(E) : 4 students