The diagram shows a light ray entering a glass block. Which calculation is used to find the refractive index of the glass?
- A$\frac{\sin 40^{\circ}}{\sin 25^{\circ}}$
- B$\frac{\sin 40^{\circ}}{\sin 65^{\circ}}$
- C$\frac{\sin 50^{\circ}}{\sin 25^{\circ}}$
- D$\frac{\sin 50^{\circ}}{\sin 65^{\circ}}$