Astronomy quiz question: evening star Venus?

Astronomy 210 Quiz 2, fall semester 2013
Cuesta College, San Luis Obispo, CA

The locations of Venus, Earth, and Mars are shown in the diagram below (not to scale, and orbits have been simplified as circles instead of ellipses).

At sunset (6 PM), Venus will be:
(A) low over the east horizon.
(B) somewhere high up in the sky.
(C) low over the west horizon.
(D) not visible in the sky.

Correct answer (highlight to unhide): (D)

If a line is drawn from Earth to the sun, the observer at sunset (6 PM) is located perpendicular to that line.

Everything below that line would be below the horizon, such that Venus is not visible at sunset. (However, Mars would be visible at sunset, low above the sun on the west horizon.)

Section 70158
Exam code: quiz02sNi7
(A) : 6 students
(B) : 4 students
(C) : 26 students
(D) : 10 students

Success level: 24% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.59