Which one of the following items is affected when the MJ-1/B accelerator pedal is adjusted?

When the MJ-1/B accelerator pedal is adjusted, it directly influences the hydrostatic drive flow rate. The hydrostatic drive system is integral to the operation of the MJ-1/B; it uses a combination of hydraulic fluid and mechanical components to control speed and movement. Adjusting the accelerator pedal changes the flow rate of the hydraulic fluid, thereby affecting the power and speed of the vehicle.

The correct answer emphasizes the relationship between the accelerator pedal position and the performance of the hydrostatic drive system, which is critical for maneuvering and operation. This understanding is vital for ensuring effective control over the equipment in various operational contexts, particularly in munitions systems where precision is key.

Other options involve systems that do not directly relate to the adjustment made by the accelerator pedal. For example, while the brake system, steering performance, and air conditioning may be crucial for overall vehicle function, they do not directly depend on the position of the accelerator pedal in the same manner as the hydrostatic drive flow rate does.