Final answer:
The number of hydraulic pumps in the YELLOW system cannot be determined with the given information.
Step-by-step explanation:
In a hydraulic system, the number of hydraulic pumps depends on the specific system. The YELLOW system mentioned in the question does not provide enough information to determine the exact number of hydraulic pumps. However, hydraulic systems typically have a motorized pump that does most of the work. This pump is responsible for generating the pressure needed to operate the system.