Concept:Pressure is the force applied per unit area. When the force is constant, pressure is greatest when the contact area is smallest.
Explanation:Pressure is given by
P=AF, where
F is the man's weight and
A is the contact area.
The man's weight does not change with posture, so
F is constant.
Therefore,
P increases as
A decreases.
Lying flat on his back or belly spreads the body over a large area, giving low pressure.
Standing on both feet gives a moderate contact area.
Standing on the toes of one foot reduces the area to the smallest possible value.
Hence, the pressure exerted on the ground is greatest in this position.
Answer:D. stands on the toes of one foot