Final answer:
Body and equipment upfits requiring extra power often need a hydraulic system to handle the power requirements, similar to how trains and trolley buses use wired systems for electricity.
The correct option is D.
Step-by-step explanation:
Body and equipment upfits that require additional power to operate typically necessitate a hydraulic system.
This is because hydraulic systems are capable of providing the high level of power required to operate certain body and equipment modifications, particularly those that involve moving parts and heavy lifting.
For example, in the context of electrified transportation, vehicles like trains and trolley buses can use wires (either overhead or through a third rail) to provide the necessary electricity to power the vehicle without the need for batteries.
The correct option is D.