Astronomy current events question: asteroid Baptistina not dinosaur killer?

Astronomy 210L, fall 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!)

Whitney Clavin and Trent J. Perrotto, "Origin of Dinosaur-Killing Asteroid Remains a Mystery," September 19, 2011
http://www.nasa.gov/mission_pages/WISE/news/wise20110919.html

__________ measurements from NASA's Wide-field Infrared Survey Explorer have ruled out remnants from the asteroid Baptistina as causing the extinction of dinosaurs.
(A) Neutrino emission.
(B) Radioactive dating.
(C) Reflectivity and size.
(D) Iridium abundance.
(E) Rotation axis.

Correct answer: (C)

Student responses
Sections 70178, 70186, 70200
(A) : 8 students
(B) : 8 students
(C) : 27 students
(D) : 3 students
(E) : 3 students