Final answer:
The movement from point A to point B could be caused by a change in displacement vectors.
Step-by-step explanation:
The movement from point A to point B could be caused by a change in displacement vectors. Displacement is a vector quantity that represents the change in position of an object. It has magnitude and direction.
When your friend reaches the pond at B, his displacement vector DAB from A is the vector sum of his displacement vector ĎAD from A to D and his displacement vector DB from D to the fishing hole: ĎAB = ĎAD + ĎDB.
This means that the movement from point A to point B could be caused by a change in his displacement vectors from A to D and from D to B.