What does zero psia (pounds per square inch absolute) approximately equal at sea level?

Zero psia, or pounds per square inch absolute, refers to a pressure measurement that is referenced against a perfect vacuum. At sea level, the atmospheric pressure is approximately 14.7 pounds per square inch. Therefore, when one states that the pressure is 0 psia, it means that the pressure is equivalent to a vacuum, which is substantially lower than the atmospheric pressure that exists on the surface of the earth.

In this context, psig, or pounds per square inch gauge, measures pressure relative to atmospheric pressure. Consequently, 0 psig would indicate a pressure that is equal to atmospheric pressure, not below it. Thus, the relationship between psia and psig in this scenario clearly shows that 0 psia correlates to an absolute vacuum, while standard atmospheric pressure at sea level is 14.7 psig.

In summary, at sea level, the absolute pressure of 14.7 psia reflects the atmospheric pressure, which corresponds directly with the correct choice.