We need to find the value of the expression:
\[
M(M(A(M(x, y), S(x, y)), D(x, y)), A(x, y))
\]
Substitute \( x = 2 \) and \( y = 3 \) into the functions:
\[
A(2, 3) = 2 + 3 = 5, \quad S(2, 3) = 2 - 3 = -1
\]
\[
M(2, 3) = 2 \times 3 = 6, \quad D(2, 3) = \frac{2}{3}
\]
Now, calculate the innermost function:
\[
M(A(M(2, 3), S(2, 3))) = M(A(6, -1)) = M(6 + (-1)) = M(5) = 5 \times 5 = 25
\]
Next, apply \( D(2, 3) = \frac{2}{3} \):
\[
M(25, \frac{2}{3}) = 25 \times \frac{2}{3} = \frac{50}{3} = 16.67
\]
Finally, apply \( A(2, 3) = 5 \):
\[
M(16.67, 5) = 16.67 \times 5 = 140
\]
Thus, the answer is b. 140.