Final answer:
The stream's profile is primarily influenced by climate, rock type, and tectonics, which affect water availability, erosion resistance, and the stream's gradient and velocity.
Step-by-step explanation:
The primary factors that influence a stream's profile are climate, rock type, and tectonics. Climate affects the amount of water available through precipitation and thus influences erosion and sediment transport.
Rock type determines the stream bed's resistance to erosion, which shapes the stream's channel. Tectonic activities can change the elevation and gradient of the stream, influencing its velocity and capacity to transport material.