What would be the best next step for verifying the identity

What would be the best next step for verifying the identity below? sec^6x(sec x tan x) - sec^4x(sec x tan x) = sec^5X tan^3X sec^4x(sec x tan x)(sec^2x -1) = sec^5x tan^3x A. (1 + tan^4x)(sec x tan x)(sec^2x -1) = sec^5x tan^3x B. sec^6x(sec x tan x) - sec^4x(sec x tan x) = sec^5x tan^3x C. sec^4x(1/cos x cot x )(sec^2X - 1) = sec^5x tan^3x D. sec^4x(sec x tan x)(tan^2x) = sec^5x tan^3x

Solution

option d is correct sec^2 x -1 = tan^2 x