Apositive rod is touched to a neutral sphere.

which best explains the arrow’s purpose in the diagram?

a. it is showing the direction that protons move in, making the sphere negative.

b. it is showing the direction that protons move in, making the sphere positive.

c. it is showing the direction that electrons move in, making the sphere positive.

d. it is showing the direction that electrons move in, making the sphere negative.

Correct answer is d.

Explanation:
We know that same charges repel each other and opposite charges attract each other. Any time that we have some charge same amount of opposite charge will move in order to balance that extra charge.

We have positively charged rod. To balance this positive charge, negative charge from sphere will move towards it. The arrow shows direction in which negative charge from a sphere will move. This way surface of a sphere will become negative. Note that total charge of a sphere remains constant and it adds to zero.