Which clearance allows pilots to make stops at intermediate locations while en route?

The clearance that allows pilots to make stops at intermediate locations while en route is known as a through clearance. This type of clearance permits the aircraft to travel from its departure airport to a destination with the understanding that it may make scheduled stops or layovers at points along the route. This is crucial for flight planning as it gives pilots the flexibility to adapt to operational needs or fuel requirements at various waypoints without needing to obtain separate clearances for each stop.

In contrast, taxi clearance, takeoff clearance, and landing clearance are more specific to measures taken during the phases of flight directly associated with the airport environment. Taxi clearance pertains to the movement of an aircraft on the ground, takeoff clearance is specifically for beginning flight operations, and landing clearance relates to the final approach and arrival phase. None of these clearances provide the flexibility needed for intermediate stops as mentioned in the question.