Which gesture signals the operator to move the trolley?

• A. holding the palm of your hand up with your fingers closed, pointing your thumb in the direction of motion, and jerking your hand horizontally
• B. extending your arm forward with your hand open and slightly raised, and making a pushing motion in the direction of travel
• C. extending your arm with the palm of your hand down, and moving your arm back and forth horizontally
• D. holding your forearm vertical with your forefinger pointing up and moving your hand in a small horizontal circle

Answer: (B)