Astronomy midterm question: Cancer rising at 9:00 PM?

Astronomy 210 Midterm 1, fall semester 2013
Cuesta College, San Luis Obispo, CA

An observer in San Luis Obispo, CA watches the constellation Cancer rising at 9:00 PM. Ignore daylight saving time. What date is this?
(A) March 5.
(B) July 5.
(C) October 8.
(D) December 5.

Correct answer (highlight to unhide): (D)

Placing the constellation Cancer on the east/northeast horizon of a planisphere ("starwheel")--where it would be rising--then looking at the date that lines up with 9:00 PM shows that it is December 5.

(Response (A) is the date that Cancer would be highest overhead at 9:00 PM, and response (B) is the date that Cancer would be setting (on the west/northwest horizon) at 9:00 PM.)

Section 70158
Exam code: midterm1s73W
(A) : 8 students
(B) : 10 students
(C) : 0 students
(D) : 32 students

Success level: 66% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.59

Section 70160
Exam code: midterm1N1t3
(A) : 1 student
(B) : 12 students
(C) : 1 student
(D) : 16 students

Success level: 57% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.54