Final answer:
Texas law prohibits radar detectors, oversized spoilers, and flashing lights on passenger cars. GPS and toll transponders, while capable of tracking, are legal.
Step-by-step explanation:
Texas state law specifically forbids certain types of equipment on passenger cars in order to ensure safety and compliance with regulatory standards. The correct answer to the equipment that is forbidden by Texas law on passenger cars is b) Radar detectors, oversized spoilers, flashing lights. It's important to note that while some devices like GPS systems are widely used for navigation and can raise privacy concerns as they track and monitor people, they are not illegal to have in vehicles. Moreover, toll transponders while monitoring vehicle movement, are also legal and commonly used for paying tolls electronically without stopping. However, items such as radar detectors, which are designed to alert drivers to law enforcement radar and laser speed detection devices, are considered illegal, along with oversized spoilers that might not meet safety regulations, and flashing lights that could be confused with emergency vehicles.