Answer:
B. Results when headward erosion causes one stream to intersect the course of another stream.
Step-by-step explanation:
Headward erosion of a low level stream can extend to intersect a higher level stream and draw away its water.
The diagram below shows Stream A eroding headward into Stream B and capturing its water flow.
A.is wrong. A water gap still carries water today.
C. is wrong. The captured stream dries up, while the pirate stream increases its flow.
D. is wrong. A dramatic example did occur in the Yukon in 1916, However, stream captures do not occur frequently.