Final answer:
The set notation for selecting one letter from RAN includes the options R, A, and N.
Step-by-step explanation:
The set notation for selecting one letter from RAN would be (a) R, (b) A, or (c) N. These notations represent the individual letters that can be chosen from the set RAN. For example, if you select option (a) R, it means you are choosing the letter 'R' from the set RAN.