Astronomy current events question: retrograde planet in binary star system

Astronomy 210L, Fall 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!)

Alisdair Wilkins, "Retrograde Planets Could Survive Around Binary Stars," October 5, 2010
http://www.wired.com/wiredscience/2010/10/retrograde-binary-system/

University of Texas-Arlington researchers have proposed that a planet orbits a primary star in the opposite direction of its binary star companion, based on observations of the stars':
(A) reflected light.
(B) gravitational wobbles.
(C) eclipses.
(D) parallax.
(E) surrounding dusty disk gaps.

Correct answer: (B)

Student responses
Sections 70178, 70186, 70200
(A) : 2 students
(B) : 26 students
(C) : 2 students
(D) : 0 students
(E) : 1 student