A faint is a brief loss of consciousness of more than momentary duration caused by a temporary reduction in the flow of blood to the brain. How would you prevent anyone from fainting ?

A. If standing in a crowd, flex the leg muscles and toes to aid circulation
B. Try to keep the person in an upstanding position
C. Tell the person to sit down in a sitting position breathing normally
D. Tell the person to sit down and lean forward with the head between the knees taking deep breaths