K Use a tree diagram for the following. a. Find the number of ways 2 letters can be choosen from the set (U, V, W) if order is important and repetition is allowed. b. Reconsider part a if no repeats are allowed. c. Find the number of combinations of 3 elements taken 2 at a time. Does this answer differ from part a or b? a. The number of ways to select 2 letters from the set {U, V, W} if order is important and repetition is allowed is