Astronomy current events question: Earth's magnetic field reversal

Astronomy 210L, fall semester 2019
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!)

Eric Hamilton, "Earth's Last Magnetic Field Reversal Took Far Longer than Once Thought" (August 7, 2019)
news.wisc.edu/earths-last-magnetic-field-reversal-took-far-longer-than-once-thought/

Analysis of magnetic iron in ancient __________ provide evidence that Earth's most recent magnetic field reversal took far longer than previously estimated.
(A) tree rings.
(B) lava flows.
(C) petroglyphs.
(D) papyrus ink.
(E) plankton fossils.

Correct answer: (B)

Student responses
Sections 70178, 70186
(A) : 2 students
(B) : 34 students
(C) : 2 students
(D) : 0 students
(E) : 6 students