(A) : Magnitude of electric force acting on a proton and an electron, moving in a uniform electric field is same, where as acceleration of electron is 1836 times that of a proton.
(R) : Electron is lighter than proton.

We know that the acceleration of a proton can be mathematically represented using the equation:

 $a=\frac{qE}{m}$

From the above expression, acceleration is inversely proportional to mass. Since the mass of the electron is lesser than that of a proton, the acceleration of an electron is greater than that of an electron. 

The correct option is A