Which of the following equipment is specifically forbidden by Texas state law on passenger cars?

In Texas, the law prohibits the use of flashing red lights on the front of passenger cars because these lights are reserved for emergency vehicles. Emergency vehicles use flashing red lights to alert other drivers to their presence and signal that they need the right of way. Allowing passenger vehicles to use this type of lighting could cause confusion on the road, as other drivers might mistakenly think a non-emergency vehicle is being operated in an emergency situation. Maintaining clear visual signals and adherence to traffic laws helps ensure safety for all road users.

The other equipment options listed are permitted under Texas law for passenger vehicles. Parking lights are standard for indicating a vehicle's position when stationary, rearview mirrors are crucial for safety and visibility, and having two headlights is a requirement for proper functioning of a vehicle at night and during adverse weather conditions.