When a charged particle q move with velocity v inside a uniform magnetic field B, then force acting on it. F=q(v×B)=2qvBsinθ Since we know that, if v and B are neither orthogonal nor parallel i.e., θ≠0,90∘ and180∘ then particle will describe a helical motion. However, if v and B are perpendicular to each other. then particle will describe a circle. So, statement given in option (c) is correct.