Final answer:
Upon doubling the distance between sphere A and B, the electrostatic force between them decreases by a factor of four due to Coulomb's Law.
Step-by-step explanation:
The electrostatic force between sphere A and B is governed by Coulomb's Law, which states that the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. If the distance between sphere A and sphere B is doubled, according to Coulomb's Law, the electrostatic force between them will decrease by a factor of four (22=4). This is because doubling the distance between the charges results in the square of the distance increasing by a factor of four, causing the force to be one-fourth of its original strength.