I believe the answer is "abnormal psychology"
Answer:
D. By adding the vectors

Explanation:
Given
Represent the velocity of the river current as VR

Represent the velocity of the boat as VB

Required
How to calculate the velocity of boat relative to river current
From the question, we understand that both move in the same direction.
So, the relative velocity V is calculated as:



Notice that the both velocities are added together to get the relative velocities.
This is so because they both move in the same direction
<em>From the list of given options, only option D is correct.</em>
False they don't have to be clearly just has long as you have them so my teacher says!
<span>B) The nail moved to the magnet is the answer</span>