What reporting value represents a visibility of 3 miles?

The reporting value that represents a visibility of 3 miles is expressed as "3SM." In aviation and meteorological reporting, visibility is recorded in statute miles. Therefore, when reporting visibility, it is common to see values stated in this format.

In this case, "3SM" directly indicates a visibility of three statute miles, making it the correct representation for that measurement. It's crucial for pilots and air traffic control to clearly understand visibility reports, as it impacts flight operations.

Other options, while they all imply visibility, do not accurately reflect three miles. Thus, "3SM" is the precise and unambiguous way to communicate that particular visibility measurement.