Astronomy current events question: Phobos annular solar eclipse

Astronomy 210L, fall semester 2013
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!)

Guy Webster, "NASA Mars Rover Views Eclipse of the Sun by Phobos," August 28, 2013
http://www.jpl.nasa.gov/news/news.php?release=2013-263

NASA's Mars rover Curiosity observed an annular eclipse of the sun by Mars' moon, Phobos, which is:
(A) on a collision course with Mars' other moon, Deimos.
(B) an indication of a hollow core.
(C) viewable now because of solar flares.
(D) about to burn up in Mars' atmosphere.
(E) too small to completely cover the sun.

Correct answer: (E)

Student responses
Sections 70178, 70186, 70200
(A) : 1 student
(B) : 0 students
(C) : 2 students
(D) : 2 students
(E) : 55 students