An objective question in the Physics paper of Class 12 examination Codes 55/4/3, 55/4/2,55/4/1 conducted  by CBSE was not clear with the options.

Q. The trajectory of alpha particles in the scattering experiment depends on

a) Source only  b) Impact parameter only c)Source and impact parameter d)Impact parameter and screen material of the detector.

The actual answer for this question should have been energy of alpha particles and the impact parameter. This could translate to either Source and impact parameter or only Impact parameter as different sources don't always mean different energies. Two different sources may give rise to the same trajectory. 

We therefore request the board to grant marks for both the answers which are

Impact parameter only, and , Both impact parameter and source.