If a Drive Gear Is Required to Rotate a Driven

If a drive gear is required to rotate a driven gear in the same direction of rotation,which of the following is a requirement?

A) drive gear must be larger in diameter than the driven gear
B) drive gear must double the number of teeth on the driven gear
C) idler gear is required between the drive and driven gears
D) two tooth-meshed gears always turn in the same direction