27. Let $h ( x ) = \min \{ x ; x 2 \}$, for every real number of $x$. Then :\\
(A) $h$ is continuous for all $x$\\
(B) $h$ is differentiable for all $x$\\
(C) $\mathrm { h } ^ { \prime } ( \mathrm { x } ) = 1$, for all $\mathrm { x } > 1$\\
(D) $h$ is not differentiable at two values of $x$\\