Astronomy current events question: "Planet X" clues from "extreme" dwarf planet 2015 TG387's orbit

Astronomy 210L, fall semester 2018
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!)

Scott Sheppard, "New Extremely Distant Solar System Object Found During Hunt for Planet X" (October 2, 2018)
carnegiescience.edu/news/new-extremely-distant-solar-system-object-found-during-hunt-planet-x

The __________ of the "extreme" dwarf planet 2015 TG387 may indicate the presence of a still undiscovered "Planet X" at the edge of the solar system.
(A) orbit.
(B) moons.
(C) albedo.
(D) composition.
(E) radioactivity.

Correct answer: (A)

Student responses
Sections 70178, 70186
(A) : 15 students
(B) : 3 students
(C) : 0 students
(D) : 2 students
(E) : 3 students