Which famous message was sent using Morse code?

The message "SOS" is widely recognized as a distress signal in Morse code due to its simplicity and unmistakable rhythm. It consists of three short signals (dots), followed by three long signals (dashes), and concluded with another three short signals (dots), forming a clear and easily recognizable pattern. This makes it effective for communication in emergency situations, even in adverse conditions where clarity is crucial. The use of "SOS" was officially adopted in the early 20th century and remains a symbol for calling for help around the world.

In contrast, the other options are not associated with Morse code. "I have a dream," "To be or not to be," and "The only thing we have to fear is fear itself" are famous quotes from influential speeches but do not hold the same historical significance in communication as "SOS." Thus, "SOS" stands out as the correct answer for being a famous message transmitted using Morse code.