Astronomy current events question: no evidence of 'Planet X' nor companion star in outer solar system

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!)

Whitney Clavin and J.D. Harrington, "NASA's WISE Survey Finds Thousands of New Stars, But No 'Planet X'," March 7, 2014
http://www.jpl.nasa.gov/news/news.php?release=2014-075

An extensive search by NASA's Wide-Field Infrared Survey Explorer has ruled out the existence of __________ in the outer solar system.
(A) a companion star or another jovian planet.
(B) extraterrestrial life.
(C) a protective magnetosphere.
(D) cosmic ray sources.
(E) antimatter production.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 34 students
(B) : 1 student
(C) : 1 student
(D) : 2 students
(E) : 4 students