Final answer:
Inches of water column ("WC) is a unit of gas pressure, with 27.7 inches of WC equaling 1 psi, which is the correct answer option A.
Step-by-step explanation:
Inches of water column ("WC) is a unit used to measure gas pressure, particularly in applications like heating, ventilation, and air conditioning. It represents the pressure exerted by a column of water that is one inch high. The conversion between inches of water column and pounds per square inch (psi) is that 27.7 inches of water column equals 1 psi. This is because the atmospheric pressure at sea level, which is 1 atmosphere (atm), is equal to 14.7 psi and also equivalent to a water column of approximately 406.4 inches. Therefore:
1 psi = (14.7 psi/atm) × (406.4 inches WC/atm) ≈ 27.7 inches WC.