Answer:
The statements A and D are true
The statements B and C are false
Explanation:
The force between charges can be explained by the Coulomb's Law.
According to Coulomb:
1 - Like charges always repel each other
2- Unlike or opposite charges always attrack each other
3- Force between 2 charges is given by:

where F is the force between 2 charges and r is the distance between 2 charges.
We can see that Force F is inversely proportional to the distance r
Which means that when F increase, r decreases and when F decreases, r increases
C) is the correct answer.
A. the medium
For refraction to occur, there has to be change from one medium to another. For example rays of light would refract as the travel from air to water.