Which statement about DOP is true?

• A. DOP increases when satellite geometry improves.
• B. DOP depends only on time of day.
• C. DOP decreases with better geometric spread of satellites.
• D. DOP is a measure of atmospheric delay.

Answer: (C)

DOP measures how the arrangement of satellites in the sky influences how errors in the measurements translate into errors in the computed position. When satellites are well spread out around you, the geometry gives strong constraints, so the same measurement errors have less impact on the final position—DOP becomes smaller. If satellites cluster in a small portion of the sky, the geometry is weak and those errors get amplified, making the position less precise—DOP becomes larger. So as the geometric spread of satellites improves, DOP decreases, which is why this statement is true.

Other ideas don’t fit because DOP isn’t about what time of day it is or atmospheric delays; it’s about satellite geometry.