To convert psi to feet of head, you should:

The correct method to convert psi (pounds per square inch) to feet of head is to multiply psi by 2.31. This conversion is based on the relationship between pressure and the height of a liquid column in a gravitational field. The factor of 2.31 comes from the density of water and the acceleration due to gravity, which allows for the translation of pressure measurements into a height measurement.

In this context, one psi can support approximately 2.31 feet of water. Hence, multiplying the pressure in psi by this factor gives you the height in feet of the water column that corresponds to that pressure. This is particularly useful in plumbing design, where understanding pressure in terms of vertical height can assist in determining the necessary pump specifications or system requirements.

Other options provided do not reflect the correct conversion principles involved in pressure and height, making them unsuitable for this specific calculation. Thus, to accurately convert psi to feet of head, the multiplication by 2.31 is the correct approach.