What letters make up the international distress signal?

The international distress signal is represented by the letters "SOS." This signal has become widely recognized as a universal call for help, particularly in emergency situations at sea. The choice "SOS" is not an acronym but rather a Morse code sequence that is easy to recognize. In Morse code, "S" is represented by three short signals (dots), followed by "O," which is represented by three long signals (dashes), and then it concludes with another "S." This combination creates a simple, distinctive, and easily communicated signal that can be transmitted in various ways, including via radio or light.

The other choices do not correspond to any recognized international distress signals. For example, "SOP," "DIST," and "HELP" are not established signals used for indicating distress in maritime or aviation context. Thus, "SOS" stands out as the correct and standard distress signal used globally.