The pressure exerted on the ground is determined by the force applied and the area over which the force is distributed.

Option 1 suggests that lying down on the ground would result in the greatest pressure. However, this is not correct. When a person lies down, their weight is distributed over a larger area, resulting in lower pressure.

Option 2 states that the pressure is greatest when a person stands on the toes of one foot. This is true because the weight of the person is concentrated on a smaller area when standing on one foot, resulting in higher pressure.

Option 3 suggests that standing with both feet flat on the ground would result in the greatest pressure. However, this is not correct. When both feet are flat on the ground, the weight is distributed over a larger area, resulting in lower pressure.

Option 4 states that all of the above yield the same pressure. This is not correct. As discussed above, the pressure exerted on the ground varies depending on the distribution of weight.

In conclusion, option 2 is the correct answer because standing on the toes of one foot concentrates the weight on a smaller area, leading to the greatest pressure.