Astronomy current events question: Earth's core hotter than previously modeled

Astronomy 210L, spring 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!)

Sebastian Anthony, "Earth's Core Is Much Hotter than Previously Thought--Hotter than the Surface of the Sun," April 26, 2013
http://www.extremetech.com/extreme/154357-earths-core-is-much-hotter-than-previously-thought-hotter-than-the-surface-of-the-sun

French researchers revised higher estimates of Earth's core temperature based on measuring the properties of iron:
(A) from micrometeorites.
(B) produced in the sun's core.
(C) squeezed between two diamonds.
(D) in volcanic calderas.
(E) placed in experimental fusion reactors.

Correct answer: (C)

Student responses
Sections 30678, 30679, 30680
(A) : 3 students
(B) : 7 students
(C) : 19 students
(D) : 9 students
(E) : 12 students