Upper limb observations of the Moon are used more frequently than those of the Sun because of the location of the Moon in the sky and the __________.

Correct Answer: Option A — phase of the Moon

Upper limb observations of the Moon are frequently selected over lower limb sights depending on the lunar phase. When the lower limb is unilluminated or indistinct due to the moon's phase, navigators must use the upper limb to secure an accurate sight, per Bowditch.