Astronomy midterm question: low waning crescent moon in twilight sky

Astronomy 210 Midterm 1, spring semester 2016
Cuesta College, San Luis Obispo, CA

Shown at right is a photograph[*] published with the following caption:

The Golden Gate Bridge framed the [low] crescent shaped moon perfectly as viewed [facing south] from the Marin headlands of Sausalito.

Assuming that this is a twilight sky (dark, but not completely dark) in this photograph, discuss why this caption is plausibly correct. Support your answer using a diagram showing the positions of the sun, moon, Earth, and an observer on Earth.

[*] Frederic Larson (April 5, 2005) for The Chronicle, in Katie Dowd, "83 Years Ago Today, Construction Started on the Golden Gate Bridge," January 5, 2016, 
sfgate.com/bayarea/article/83-years-construction-starts-on-golden-gate-bridge-6735946.php#photo-3097833.

Solution and grading rubric:

• p:
  Correct. Complete diagram and reasoning includes the following explanations:
  1. identifies the waning crescent moon, which rises at 3 AM, is highest overhead at 9 AM, and sets at 3 PM;
  2. sky is "dark, but not completely dark," so the photograph must have been taken just before sunrise (approximately 5-6 AM);
  3. this range of "twilight" times is consistent with the moon being "low," (still rising and not yet highest overhead), but before the sunrise.
• r:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
• t:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least attempts to draw a moon phase diagram and apply rise/overhead/set times.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. Discussion not clearly based on a moon phase diagram.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.

Grading distribution:
Section 30674
Exam code: midterm01n0rD
p: 8 students
r: 3 students
t: 4 students
v: 4 students
x: 3 students
y: 0 students
z: 0 students

Section 30676
Exam code: midterm01sN0w
p: 23 students
r: 8 students
t: 5 students
v: 10 students
x: 8 students
y: 0 students
z: 0 students

A sample "p" response (from student 8211):