Which of the following is true about dry saturated steam?

Dry saturated steam refers to steam that is fully vaporized at a specific pressure or temperature without any liquid water present. This distinguishes it from wet steam, which contains a mixture of water and vapor. In the case of dry saturated steam, the absence of water particles means that it is a pure vapor, making this characteristic essential for applications where moisture content can affect performance, such as in turbine operation or heating systems.

The other options do not accurately describe dry saturated steam. For instance, if steam contained both liquid and vapor phases, it would be classified as wet steam. Additionally, dry saturated steam exists precisely at the saturation temperature corresponding to its pressure, not below it. Lastly, while dry saturated steam can exist at various pressures, it can also be at pressures above, equal to, or below atmospheric pressure, depending on the system it's in, making the idea that it is always at a lower pressure incorrect.