Time taken by light to travel in two different materials A and B of refractive indices ?_A and ?_B of same thickness is t₁ and t₂ respectively. If t₂ – t₁ = 5 × 10^–10 s and the ratio of ?_A to ?_B is 1 : 2. Then, the thickness of material, in meter is: (Given v_A and v_B are velocities of light in A and B materials, respectively.)

(A) 5 × 10^-10 v_A m

(B) 5 × 10^-10 m

(C) 1.5 × 10^-10 m

(D) 5 × 10^-10 v_B m