Astronomy current events question: meteorite gold source

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!)

Leila Battison, "Meteorites Delivered Gold to Earth," September 8, 2011
http://www.bbc.co.uk/news/science-environment-14827624

Tungsten concentrations in different age rocks may support the theory that:
(A) many dinosaurs survived the Chicxulub asteroid impact.
(B) Earth's core is made of tungsten, rather than iron.
(C) the moon is rich in tungsten deposits.
(D) most gold in Earth's crust came from asteroids.
(E) Earth's supply of tungsten is dwindling due to radioactive decay.

Correct answer: (D)

Student responses
Sections 70178, 70186, 70200
(A) : 1 student
(B) : 2 students
(C) : 7 students
(D) : 34 students
(E) : 4 students