What is the answer associated with the Greek letter "M"?

The Greek letter "M" corresponds to the letter "Mu." In the Greek alphabet, Mu is the twelfth letter, and it is represented as 'Μ' in uppercase and 'μ' in lowercase. Each letter in the Greek alphabet has its own unique position and value.

In the context of the other options, Nu is a different letter that comes after Mu, Pi is a letter that represents the value of "P," and Iota is yet another distinct letter, representing the value of "I." Therefore, Mu is the accurate answer associated with the Greek letter "M." Understanding the sequence and position of each letter in the Greek alphabet is crucial for recognizing their designations and values.