A light balloon filled with helium of density `rho_(He)` is tied to a long light string of length  and the string is attached to the ground. If the balloon is displaced slightly in the horizontal direction from the equilibrium and released then .

Options

A. The ballon undergoes simple harmonic motion with period `2pisqrt(((rho_(air))/(rho_(air)-rho_(He)))(l)/(g))`
B. The ballon undergoes simple harmonic motion with period `2pisqrt(((rho_(air)-rho_(He))/(rho_(air)))(l)/(g))`
C. The ballon undergoes simple harmonic motion with period `2pisqrt(((rho_(He))/(rho_(air)-rho_(He)))(l)/(g))`
D. The ballon undergoes conical oscillations with period `2pisqrt(((rho_(air)+rho_(He))/(rho_(air)-rho_(He)))(l)/(g))`

Answer

C