Which theoretical minimum number of measurements from satellites does a GPS receiver need in order to provide an exact three-dimensional position?

Correct Answer: Option B — Four

GPS receivers require four satellites to solve for four unknowns: latitude, longitude, altitude, and time offset. While three satellites can provide a 2D position if altitude is assumed, a precise 3D position necessitates a fourth satellite to resolve the timing discrepancy between the receiver clock and satellite atomic clocks.