fDistance between the plates of a parallel plate capacitor is d and area of each plate is A. When a slab of dielectric constant K and thickness t is placed between the plates, its capacity becomes

a. ∊₀A / [d + { 1 - 1/k}]
b. ∊₀A / [d + { 1 + 1/k}]
c. ∊₀A / [d - { 1 + 1/k}]
d. ∊₀A / [d - { 1 - 1/k}]