Which code is accessible only by the military and is broadcast on the L1 and L2 frequencies?

The P code, also known as the precise code, is a type of GPS signal that is encrypted and exclusively available to authorized military users. It operates on the L1 and L2 frequencies. The P code provides high-precision positioning information, which is critical for military applications. It allows for greater accuracy and resistance against jamming compared to the civilian code, enabling the military to maintain operational integrity in various environments.

The C/A code is the civilian accessible code, which does not offer the same level of precision as the P code. The Y code is another type of encrypted signal primarily used with advanced military GPS receivers but is not universally recognized in the same context as the P code. PDOP, or Position Dilution of Precision, is a measure of the geometrical strength of the GPS satellite configuration and is not a code transmitted by GPS satellites. Thus, the P code is the correct answer regarding a signal exclusive to military use broadcast on the L1 and L2 frequencies.