If R = Earth's radius, h = orbit height, β = coverage angle, and θ = minimum elevation angle, then which one of the following relations is correct?

A. $$\frac{R}{{R + h}} = \frac{{\cos \left( {\beta + \theta } \right)}}{{\cos \left( \theta \right)}}$$

B. $$\frac{R}{h} = \frac{{\cos \left( \beta \right)}}{{\cos \left( \theta \right)}}$$

C. $$\frac{h}{R} = \frac{{\cos \left( {\beta + \theta } \right)}}{{\cos \left( \beta \right)}}$$

D. $$\frac{{R + h}}{h} = \cos \left( {\beta + \theta } \right) - \cos \left( \theta \right)$$

Answer: Option A