a negatively - charged plastic comb and a negatively - charged rubber balloon are brought closer together…

Explanation:

Step1: Recall Coulomb's law

The electric - force between two charged objects is given by $F = k\frac{q_1q_2}{r^2}$, where $k$ is the Coulomb's constant, $q_1$ and $q_2$ are the charges of the two objects, and $r$ is the distance between them.

Step2: Analyze the change in distance

Here, $q_1$ and $q_2$ remain constant as the charges on the comb and balloon do not change. When they are brought closer together, the distance $r$ between them decreases.

Step3: Determine the change in force

Since $F = k\frac{q_1q_2}{r^2}$, and $r$ decreases while $q_1$, $q_2$, and $k$ are constant, the value of $F$ increases.

Answer:

A. The electric force increases.