What component keeps the collector tank pressurized?

The correct choice is based on the functionality of the fuel system in the T-6B aircraft. Two transfer jet pumps are responsible for maintaining pressure in the collector tank. These pumps are critical in ensuring that fuel remains available in the collector tank for the primary jet pump to draw from, maintaining adequate feed pressure for the engine.

Having two transfer jet pumps provides redundancy, ensuring that if one pump fails, the other can still perform its function, thus enhancing reliability during flight operations. This dual-design is essential for aircraft safety, especially during critical phases of flight.

The other options do not serve this primary role of maintaining pressure in the collector tank. The electrical boost pump, for instance, is used to assist with fuel delivery under certain conditions, but it is not solely responsible for pressurizing the collector tank. Similarly, the primary jet pump is designed to draw fuel from the collector tank to feed into the engine but does not pressurize the tank itself. Therefore, the function of the two transfer jet pumps is crucial in this context.