Astronomy current events question: detecting dark matter with GPS

Astronomy 210L, fall semester 2014
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!)

Mike Walterbeek, "Hiding in Plain Sight: Elusive Dark Matter May Be Detected with GPS," (November 17, 2014)
http://www.unr.edu/nevada-today/news/2014/finding-dark-matter

University of Nevada, Reno researchers proposed detecting dark matter by tracking:
(A) GPS time signal discrepancies.
(B) sunspots.
(C) Voyager 2 signals from outside the solar system.
(D) star formation rates.
(E) changes in Earth's rotation rate.

Correct answer: (A)

Student responses
Sections 70178, 70186
(A) : 25 students
(B) : 3 students
(C) : 5 students
(D) : 5 students
(E) : 1 student