A car travels for m hours at the rate of w km/hour and then for k hours at the rate of h km/hour. The average rate for the distance covered is

A

$$\frac{mw + hk}{2}$$

B

$$\frac{mw + hk}{m + k}$$

C

$$\frac{m + h}{2}$$

D

$$\frac{2}{m + h}$$