A particle of mass m undergoes oscillations about x = 0 in a potential given by `V(x)=(1)/(2)kx^(2)-v_(0)cos((x)/(a))`, where `V_(0)`,K,a are constants. If the amplitude of oscillation is much smaller than a, the time period is given by-

Options

A. `2pisqrt((ma^(2))/(ka^(2)+V_(0)))`
B. `2pisqrt((m)/(k))`
C. `2pisqrt((ma^(2))/(V_(0)))`
D. `2pisqrt((ma^(2))/(ka^(2)-V_(0)))`