In a race, there are 4 members in a team. Each member has to cover 5 km one after another. If the total time taken is 30 minutes, then what would have been the average speed?

A

50 $$\frac{km}{hr}$$

B

40 $$\frac{km}{hr}$$

C

50 $$\frac{m}{sec}$$

D

40 $$\frac{m}{sec}$$