Astronomy current events question: K-Pg asteroid impact ocean acidification

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!)

Jim Shelton, "Mystery Solved: Ocean Acidity in the Last Mass Extinction" (October 21, 2019)
news.yale.edu/2019/10/21/mystery-solved-ocean-acidity-last-mass-extinction

Researchers confirmed that ocean acid levels rose sharply following the K-Pg asteroid impact, based on analyzing the chemical composition of __________ fossils.
(A) mammal.
(B) plankton.
(C) dinosaur.
(D) protobird.
(E) protowhale.

Correct answer: (B)

Student responses
Sections 70178, 70186
(A) : 0 students
(B) : 33 students
(C) : 1 student
(D) : 1 student
(E) : 3 students