Astronomy current events question: recurrent U Scorpii nova

Astronomy 210L, Spring Semester 2010
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, "Long-Anticipated Eruption of U Scorpii Has Begun," January 28, 2010
http://www.astronomy.com/asy/default.aspx?c=a&id=9020

U Scorpii is a star that is starting a recurrent nova explosion. What causes this?
(A) A star is feeding hydrogen onto the outer layers of a white dwarf.
(B) The core of a massive star has finally exhausted its hydrogen supply.
(C) The eruption of magnetic fields surrounding an unstable supergiant.
(D) Too much iron in the core of a supergiant.
(E) Bipolar jets from a companion neutron star.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 45 students
(B) : 13 students
(C) : 6 students
(D) : 1 student
(E) : 3 students