Rohan divides his complete journey in three equal parts and covers the first part at a speed of 30 km/h, the second part at 40 km/h and the last part at 50 km/h with his car. What is the average speed (in km/h) of his car during his entire journey?

A

$$38\frac{14}{47}$$

B

$$35\frac{14}{47}$$

C

40

D

45