Let $f$ be a function that is continuous on the closed interval $[ 2,4 ]$ with $f ( 2 ) = 10$ and $f ( 4 ) = 20$. Which of the following is guaranteed by the Intermediate Value Theorem?
(A) $f ( x ) = 13$ has at least one solution in the open interval $( 2,4 )$.
(B) $f ( 3 ) = 15$
(C) $f$ attains a maximum on the open interval $( 2,4 )$.
(D) $f ^ { \prime } ( x ) = 5$ has at least one solution in the open interval $( 2,4 )$.
(E) $f ^ { \prime } ( x ) > 0$ for all $x$ in the open interval $( 2,4 )$.