Assertion (A): Force between two point charges at rest is not changed by the presence of a third point charge between them.

Reason (R): Force between two charges depends on the magnitude of the two charges and separation between them

We know that force between two charges q₁and q₂ separated by distance “d” is given by $\mathrm{F}=\mathrm{k}\frac{{\mathrm{q}}_1{\mathrm{q}}_2}{{\mathrm{d}}^2}$
                                         
It does not depend upon any other charge present in between them. (through the net force changes but force between two charges does not change).