In a cylindrical region uniform magnetic field is present as shown in the figure. The cylinder is kept on a horizontal plane and its axis is horizontal. If a charge particle of mass m and charge q is projected horizontally with velocity v through a hole normal to the axis of the cylinder as shown
in the diagram. An observer states the particle moves first undeviated and subsequently

• A

  oscillates inside cylinder along a horizontal diameter passing through axis of the cylinder with time period $\frac{4\mathrm{RqB}}{\mathrm{mg}}$

• B

  oscillates inside cylinder along a horizontal diameter passing through axis of the cylinder with time period $\frac{2qRB}{\mathrm{mg}}$

• C

  oscillates inside cylinder along a horizontal diameter passing through axis of the cylinder with time period $\frac{\mathrm{mg}}{\mathrm{qBR}}$

• D

  It is not possible for the particle to oscillate in this given situation.