ANS:B - 34 ft ofH₂O

Atmospheric pressure can be measured in various units, and each unit corresponds to a specific hydrostatic head. The most commonly used units for atmospheric pressure are millimeters of mercury (mmHg), inches of mercury (inHg), pascals (Pa), and atmospheres (atm). Let's convert some of these units to hydrostatic heads:

1. 1 mmHg: This is equivalent to the pressure exerted by a column of mercury 1 millimeter high. The conversion factor is approximately 1 mm13.6 mm13.6mm1mm​ (since atmospheric pressure is approximately 760 mmHg, and 1 atm is equivalent to 13.6 mmHg).
2. 1 inch of mercury (inHg): This is equivalent to the pressure exerted by a column of mercury 1 inch high. The conversion factor is approximately 1 in0.535 in0.535in1in​ (since 1 inch is approximately 0.535 cm).
3. 1 pascal (Pa): This is equivalent to the pressure exerted by a force of 1 newton per square meter.
4. 1 atmosphere (atm): This is defined as the pressure exerted by a column of mercury 760 mm high at 0°C at sea level and standard gravity. The conversion factor is approximately 760 mm13.6 mm13.6mm760mm​.

Given the provided options, "13.6 meters of Hg" corresponds to atmospheric pressure. This is because atmospheric pressure is commonly measured in millimeters of mercury (mmHg), and 1 atmosphere is approximately equal to 760 mmHg, which is approximately equal to 13.6 meters of mercury. Therefore, 13.6 meters of Hg corresponds to atmospheric pressure.