White # 18 is supposed to choose possibility # 4.

Since Red also has to make his pit stop yet, White # 18 should take the chance to pass Red. That is why possibility # 1 is dropped.

Which of the remaining three possibilities is the best depends on how to estimate the forthcoming reaction of the opponents.

The leading Turquoise will start his next move from a square with speed limit. So he can take just one die and choose the left lane. Except rolling a 6 he can block the lane White # 18 has to take to drive into the pits.

If White # 18 had chosen possibility # 2, he has to drive with two dice except White # 19 succeeds in blocking the whole track. However, this does not work if White # 19 rolls 1-4 or 11-12. In this case White # 18 cannot avoid being forced to use the inner lane and fail to enter the pit lane by rolling 9 or more. Thus Possibility # 2 is also dropped.

If White # 18 had chosen possibility # 3, he is allowed to make his next move with only one die as a result of the speed limit beside the square he starts from. If he rolls 1-3 the track remains open. When this happens, White # 19 can try to block the track by driving with only one die too. If he rolls 5 or 6 there is a risk for White # 18 to be passed by Red, which of course is a must to avoid. That is why possibility # 3 is actually not optimal at all.

If White # 18 had chosen possibility # 4, he is allowed to use the special die for his next move. Rolling 2 or 3 (probability 5:6) his team mate White # 19 can definitely block the track by any roll with one die. In case White # 18 rolls only a 1 and afterwards White # 19 a 6, White # 19 can change to the inner lane. This also blocks the track, and Red is unlikely to risk his following move with two dice. With but only one die Red cannot pass White # 18. That is why possibility # 4 is the best option make White # 18 enter the pit lane.