A proton is moving with a uniform velocity of \(\$ 0 \mathrm{~ns}^{-1}\) along the \(Y\)-axis, under the joint action of a magnetic field aloig \(Z\)-axis and an electric field of magnitude \(2 \times 10 \mathrm{Vm}^{-1}\) along the negativeX-axis. If the electric field is switched off, the proton starts moving in a circle. The radius of the circle is nearly \(\left(\right.\) given \(\frac{e}{m}\) ratio for proton \(\left.=10 \mathrm{Ckg}^{-1}\right)\)
(A) \(0.5 \mathrm{~m}\)
(B) \(0.2 \mathrm{~m}\)
(C) \(0.1 \mathrm{~m}\)
(D) \(0.05 \mathrm{~m}\)