Explanation

Using a³ ± b³ = (a ± b)(a² ∓ ab + b²): the first fraction equals sin²θ − sinθcosθ + cos²θ = 1 − sinθcosθ, and the second equals sin²θ + sinθcosθ + cos²θ = 1 + sinθcosθ. Adding gives 2. This is option (c).