Which statement about straight streams is correct?

The statement that a straight stream is discharged from an adjustable fog nozzle is accurate because adjustable fog nozzles can create both straight streams and fog patterns. The use of a straight stream is beneficial in providing a concentrated and powerful flow of water, which can be directed effectively at a fire, allowing for maximum penetration and reach.

Typically, adjustable fog nozzles allow the operator to modify the pattern of the water discharge, including switching between a straight stream and a fog pattern depending on the situation and the fire conditions. In scenarios requiring a straight stream, operators can easily make this adjustment to direct the flow efficiently.

The other options present misunderstandings about straight streams. For instance, it is incorrect to say that a straight stream can only be discharged from a master stream nozzle, as various nozzles including smaller hand-held ones can also produce a straight stream. Claiming that a straight stream should always be used for interior firefighting overlooks situations where a fog pattern may be more suitable, especially in reducing heat and smoke. Lastly, asserting that a straight stream has the lowest cooling effect misconstrues the nature of water application, since straight streams actually have a higher impact and can cool fire spaces more effectively than a dispersed fog pattern in certain conditions.