Astronomy current events question: merging white dwarfs

Astronomy 210L, Spring Semester 2011
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!)

Astronomy.com editors, "Two Dying Stars Reborn as One," April 7, 2011
http://astronomy.com/en/News-Observing/News/2011/04/Two%20dying%20stars%20reborn%20as%20one.aspx

Two white dwarfs orbiting each other will merge and become a single helium-fusing star, because:
(A) their orbital energy is being lost as gravitational waves.
(B) of perturbations caused by a passing black hole.
(C) of a nearby type II supernova.
(D) they will both expand as supergiants.
(E) their gravitational pull increases from heavy element fusion.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 8 students
(B) : 0 students
(C) : 2 students
(D) : 1 student
(E) : 14 students