(5) The area of the region enclosed by the graph of the function $y=\mathrm{e}^{x}$, the line $x=0$, and the line $y=\mathrm{e}$ is ( ).
(A) 1
(B) $\mathrm{e}-1$
(C) e
(D) $2 \mathrm{e}-1$
(5) A Hint: It is $\int_{0}^{1}\left(\mathrm{e}-\mathrm{e}^{x}\right) \mathrm{d} x=1$.

