What is the Greek letter associated with the symbol "Θ"?

The Greek letter associated with the symbol "Θ" is Theta. In the Greek alphabet, Theta is the eighth letter and is commonly used in various mathematical and scientific contexts to represent angles or other concepts. It is distinctly recognizable and is often represented in uppercase as "Θ" and in lowercase as "θ". This letter holds significance in fields such as physics, engineering, and mathematics, often denoting angular measurements, temperature, or a phase in various equations.

The other options—Iota, Mu, and Nu—represent different letters in the Greek alphabet and do not correspond to the symbol "Θ". Each of these letters has its own unique sound and context within the Greek language and various academic disciplines, but they are not the correct answer for this particular symbol. Thus, focusing on the identification of "Θ" leads to the understanding that it is indeed Theta that corresponds with this symbol.