Final answer:
The strength of the electrical force between two objects increases as the amount of charge on the objects increases.
Step-by-step explanation:
The strength of the electrical force between two objects increases as the amount of charge on the objects increases. This relationship is explained by Coulomb's Law, which states that the force between two charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
For example, if you have two objects with charges of +2C and +4C, the force between them would be greater than if the charges were +1C and +2C. Similarly, if the distance between the objects is halved, the force between them would quadruple.
Therefore, the correct answer is a. increases.