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>
Answer:
C) It is impossible to have identical twins of different sexes
Explanation:
Scientifically monozygous or identical twins are usually of the same sex unless in a rare case of genetic mutation where they develope into different sexes.
When the individual asked if they are identical twins, the first line of thought naturally will be to think if it is possible to have identical twins of different sexes
Specific Description. It's neither biased nor inappropriate, since both are factually true and informing about Stephanie. And it's not a cliched statement either.