Which is the Greek letter that corresponds to 'Y'?

The Greek letter that corresponds to 'Y' is Upsilon. Upsilon is the 20th letter of the Greek alphabet and is represented in uppercase as 'Υ' and in lowercase as 'υ'. In the context of the Greek alphabet, Upsilon is often associated with the English 'Y' sound, making it the correct answer to this question.

On the other hand, the other options represent different letters: Nu corresponds to 'N,' Lambda corresponds to 'L,' and Kappa corresponds to 'K.' Understanding the relationships between Greek letters and their English counterparts can help solidify knowledge of the Greek alphabet as well as their usage in various contexts, such as mathematics, science, and fraternity/sorority life.