What is the name of the line through which fuel is routed from the engine-driven low pressure fuel pump to the primary jet pump?

The motive flow line is the correct term used to describe the pathway that directs fuel from the engine-driven low-pressure fuel pump to the primary jet pump. This line is integral to the operation of the fuel system, allowing the low-pressure fuel pump to deliver fuel effectively to the jet pump, which subsequently ensures the appropriate fuel flow and pressure necessary for the engine's operation. The motive flow line plays a crucial role in maintaining the overall functionality and efficiency of the fuel system in an aircraft, particularly in ensuring that fuel is available at the correct pressure for proper engine performance.

The other line types referenced, such as the fuel return line, pressure line, and output line, have specific functions but do not accurately describe the connection between the low-pressure fuel pump and the primary jet pump in this context. Each of these lines serves different purposes, such as routing excess fuel back to the tank, managing pressure levels, or conveying fuel to various components, but it is the motive flow line that specifically connects the low-pressure pump to the jet pump.