21. If 2 < a < 5, and 3 < b < 6, what are the possible values of a + b?
(A) a + b must equal 8.
(B) a + b must be between 2 and 6.
(C) a + b must be between 3 and 5.
(D) a + b must be between 5 and 8.
(E) a + b must be between 5 and 11.