Final answer:
Historical vehicle regulations typically required trucks made before 1960 to have at least A. one tail-light. Mirrors and light bulbs with multiple power settings provide illustrative examples of how historical standards and configurations varied for different equipment.
Step-by-step explanation:
The question refers to the vehicle equipment regulations for trucks manufactured or assembled prior to the year 1960. While modern vehicles are typically required to have two tail-lights for safety reasons, older vehicles may have different requirements based on the laws and standards that were in effect at the time they were made.
Without specific jurisdictional context, the general historical standard for vehicles of that era would typically be one tail-light, as regulations have evolved over time to increase road safety. To provide a more accurate answer, one would need to consult the vehicle regulations specific to the place and time in question.
For the example involving mirrors, seeing the back of your head would require a minimum of two mirrors arranged at an angle so that the reflection from one mirror can be viewed in the second mirror.
In the case of the light bulbs with multiple power settings, a minimum of two filaments would be required for three power settings. This is because one filament can provide a low setting, and two filaments switched on together can provide a medium setting, while all can combine for the high setting.
Therefore, referring to the original question concerning the requirements for trucks before 1960, the correct option is typically: A. One tail-light.