Let (a, b). The set of strings of elements of of arbitrary length is called a "dictionary" based on the "alphabet" E. Let B and C be defined as follows: B = {WE : length(w) 2) , C (w E . : length(W2 2 } a) Determine the following sets: BUC, BC, B, C b) If possible, use roster notation to enumerate all elements of B and C c) Use roster notation to describe P (2)