A substitution takes a ‘word’ written in the letters X and Y and gives a new word by replacing each (old) X with a Y, and each (old) Y with XY. For instance, it converts YXY to XYYXY. Starting with the 1-letter word w0 = X, we get new words w1 = Y, w2 = XY, w3 = YXY, and so on with each wn + 1 obtained from wn by applying the substitution. If (l, m) is the pair with l = number of X in w10 and m = number of Y in w9. Then (l, m) = _______.(Take w0 = X)

A substitution takes a ‘word’ written in the letters X and Y and

1.	A substitution takes a ‘word’ written in the letters X and Y and gives a new word by replacing each (old) X with a Y, and each (old) Y with XY. For instance, it converts YXY to XYYXY. Starting with the 1-letter word w0 = X, we get new words w1 = Y, w2 = XY, w3 = YXY, and so on with each wn + 1 obtained from wn by applying the substitution. If (l, m) is the pair with l = number of X in w10 and m = number of Y in w9. Then (l, m) = _______.(Take w0 = X)
A.	(21, 34)
B.	(34, 34)
C.	(34, 21)
D.	(55, 34)
Answer» C. (34, 21)