Final answer:
The factor that does not contribute to GPS position error is the receiver clock error because GPS systems correct for this using the signals from multiple satellites. Option C is correct.
Step-by-step explanation:
The question asks about the factors that do not contribute to the position error of a commercial GPS receiver. The available options are a) Satellite clock error, b) Atmospheric delay, c) Receiver clock error, and d) Ionospheric delay. To understand which of these does not contribute to the position error, we need to consider how GPS works and the problems that can affect its accuracy.
GPS accuracy is dependent on precisely synchronized atomic clocks and the signal travel time between the satellite and the receiver. Discrepancies like satellite clock error, atmospheric delay, and ionospheric delay can introduce errors in determining position. Time dilation effects due to relative velocity and weaker gravity at the satellites' altitude (special and general relativity effects) mean that satellite time can differ from Earth time, contributing to possible errors.
Additionally, disturbances like Coronal Mass Ejections (CMEs) can distort satellite signals, also contributing to GPS inaccuracies. However, the receiver clock error refers to the internal clock of the GPS device itself, which typically doesn't need to maintain the same level of precision as the atomic clocks on satellites because GPS receivers use the timing from multiple satellites to correct any internal clock discrepancies.
Therefore, the correct answer is c) Receiver clock error, because it is managed and corrected by the GPS system using signals from multiple satellites, making it a non-contributory factor in GPS position error under normal circumstances.