By definition we have that the electric force is given by:
Where,
k: proportionality constant
q1: electric charge of object 1
q2: electric charge of object 2
d: distance between both objects
Therefore, to increase the electric power there are two possible cases:
1) Add more load to each object
2) Decrease the distance between objects.
The option that increases the electric force for this case is:
Electrons are added to two negatively charged objects.
This is because the values of q1 and q2 increase.
Answer:
A change that increases the electric force between objects is:
B) Electrons are added to two negatively charged objects.