A particle of charge q and mass m moving with a velocity v along the x-axis enters the region x > 0 with uniform magnetic field B along the \[\hat{k}\] direction. The particle will penetrate in this region in the x-direction upto a distance d equal to [MP PMT 1997]

• A.            Zero                                         
• B.            \[\frac{mv}{qB}\]
• C.            \[\frac{2mv}{qB}\]            
• D.            Infinity