Astronomy quiz question: blue color of a reflection nebula

Astronomy 210 Quiz 6, spring semester 2015
Cuesta College, San Luis Obispo, CA

A reflection nebula appears to be blue because its dust particles:
(A) absorb red light.
(B) scatter blue light.
(C) emit blue photons.
(D) have cool temperatures.

Correct answer (highlight to unhide): (B)

Very small dust particles will scatter short-wavelength (blue) light in all directions more than scattering longer wavelengths of visible light (all other colors), such that this nebula will appear blue in color.

Section 30676
Exam code: quiz06szLR
(A) : 3 students
(B) : 37 students
(C) : 7 students
(D) : 0 students

Success level: 81% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.46