Correct Answer - A
With respect to the cart, equilibrium position of the pendulum is shown.
If displaced by small angle `theta` from this positon, then it will execute SHM about this equilibrium position, time period of which is given by
`T=2pisqrt(L/(g_(eff))) , g_(eff) =sqrt(g^(2)+(sqrt(3g)^(2)))rArr g_(eff) =2grArr T=1.0` second