The acceleration in a body is due to ___________.

i) balanced force ii) unbalanced force

iii) electro static force

(ii) is correct.

In case of (i), balanced forces lead to zero net force. So, there is no acceleration as F = ma. For (iii), the force acts only on charged bodies. In most everyday objects, there are no excess charges and they are neutral bodies. So electrostatic force causes no acceleration on uncharged bodies. For (ii), there is a net force, so there is acceleration.