As it happens, I just had this question on my FED test:

With a runner on third base, the pitcher stops his delivery because the batter stepped out of the box with one foot because the third base coach was giving a new sign.
a. There is no penalty on either the batter or the pitcher. The umpire shall call "Time" and begin play anew.
b. Declare a balk and score the runner from third.
c. Declare an immediate strike on the batter.
d. Both B and C.

The correct answer is "A"

Explanation: 6-2-4d-1 (as others have already correctly pointed out)