A charged particle is moving in a region where a uniform gravitational field and uniform magnetic field exist (Electric field is zero). Then path of the particle may be 

detailed solution

Correct option is D

If the magnetic field is vertically down ward or vertically upward and the particle is projected vertically down ward or vertically upward. Then magnetic force F→=QV→×B→ is zero and the path is a vertical straight line. If the particle is projected vertically and the magnetic field is horizontal then the path is a helix of variable pitch.For parabolic path acceleration of the particle must be constant. But if both gravitational field g→ and magnetic field B→ exist and B→ is not parallel to g→ then acceleration of the particle cannot remain constant.