Astronomy current events question: pulsar timing detection of gravitational waves?

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!)

News release, "Gravitational Waves from Merging Supermassive Black Holes Will Be Spotted within 10 Years, New Study Predicts" (November 13, 2017)
simonsfoundation.org/2017/11/13/gravitational-waves-supermassive-black-hole-merger/

Computer simulations predict that gravitational waves from merging supermassive black holes could be detected by monitoring variations in:
(A) matter-antimatter production.
(B) dark matter densities.
(C) pulsar times.
(D) radioactive decay rates.
(E) type II supernova brightnesses.

Correct answer: (C)

Student responses
Sections 70178, 70186
(A) : 3 students
(B) : 6 students
(C) : 29 students
(D) : 4 students
(E) : 1 student