Which of the following would cause the force of static friction to increase?

Answer B)  An increase in

Explanation:

Since we are talking about the force of static friction, due to its definition as the product between the normal force to the surface times the coefficient of static friction, the only two ways such force could increase is due to an increase in the normal force, or an increase in the coefficient of static friction .

So the only valid answer is answer B)

this could be newton#'s law of cooling. the cooling curve is exponential