Aladdin is remaining with his last wish. Being very generous he wants to set Genie free by giving him his freedom. But there are certain conditions that are placed on the lamp before one can set Genie free. The lamp asks a riddle and if Aladdin is able to solve this riddle then Genie will be free. Aladdin knowing the risk involved is ready to solve the puzzle.
The lamp asks
Main track AB and two small branches AD and BD form a railroad triangle. When a locomotive goes from A to B, backs into BD, and moves forward out of AD, it has reversed its direction on AB. In how many moves does the engineer move the black car to BD and the white car to AD, and return the locomotive to face right on AB. The dead end beyond the switch at C can only hold the locomotive or 1 car. Each coupling or uncoupling is 1 move.

Options

A. 12
B. 10
C. 8
D. 6