GKFix MCQ Question

In the formula n21 = sin((A+Dm)/2) / sin(A/2) for a prism, what does 'n21' represent?

• A. Absolute refractive index of the surrounding medium
• B. Absolute refractive index of the prism material
• C. Refractive index of the prism material relative to the surrounding medium
• D. Critical angle of the prism