Astronomy current events question: star HD 162826--the sun's sibling?

Astronomy 210L, spring semester 2014
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!)

Ivan Ramirez, "Astronomers Find Sun’s ‘Long-Lost Brother,’ Pave Way for Family Reunion," May 8, 2014
http://mcdonaldobservatory.org/news/releases/2014/05/08

Observations of star HD 162826's __________ indicate that it may have been born in the same gas and dust cloud as the sun.
(A) red dwarf companion.
(B) chemical make-up and motion.
(C) Earth-like planets.
(D) asteroid belt.
(E) lack of radioactivity.

Correct answer: (B)

Student responses
Section 30682
(A) : 0 students
(B) : 19 students
(C) : 0 students
(D) : 1 student
(E) : 1 student