A pendulum suspended from the roof of an elevator at rest has a time period `T_(1)`, when the elevator moves up with an acceleration `a` its time period becomes `T_(2)`, when the elevator moves down with an acceleration `a`, its time period becomes `T_(3)`, then

Options

A. `T_1=sqrtT_2T_3`
B. `T_1=sqrt(T_2^2+T_3^2)
C. `T_1=(T_2T_3sqrt2)/sqrt(T_2^2+T_3^2)`
D. none of these