Correct Answer - A
Point `O` is moving as shown
So `acc`. Of particle `w.r.t O`
`= (-alpha_(1)hat(i) + (alpha_(2) - g)hat(j))`
So `g_(eff**) = sqrt(alpha_(1)^(2) + (g - alpha_(2)^(2))`
So time period
`= 2pisqrt((l)/((alpha_(1)^(2) + (g - alpha_(2))^(2))^(1//2)))`