A parallel plate capacitor C with plates of unit area and separation d is filled with a liquid of dielectric constant `K=2`. The level of liquid is `d//3` initially. Suppose the liquid level decreases at a constant speed v, the time constant as a function of time t is-
A. `(6 epsilon_(0)R)/(5d+3Vt)`
B. `((15d+9Vt)epsilon_(0)R)/(2d^(2)-3dVt-9V^(2)t^(2))`
C. `(6 epsilon_(0)R)/(5d-3Vt)`
D. `((15d-9Vt)epsilon_(0)R)/(2d^(2)+3dVt-9V^(2)t^(2))`
