11. If $a=\frac{2014}{2015^{2}}, b=\frac{2015}{2016^{2}}, c=\frac{2016}{2017^{2}}$, then ().
(A) $a<b<c$.
(B) $b<c<a$.
(C) $c<b<a$.
(D) $a<c<b$.
Answer: $\mathrm{C}$.

Solution:
$$
\begin{array}{c}
\frac{1}{a}=\frac{(2014+1)^{2}}{2014}=2014+2+\frac{1}{2014}, \\
\frac{1}{b}=2015+2+\frac{1}{2015}, \\
\frac{1}{c}=2016+2+\frac{1}{2016},
\end{array}
$$

That is
$$
\frac{1}{a}<\frac{1}{b}<\frac{1}{c},
$$

Therefore
$$
c<b<a \text {. }
$$

Hence, the correct choice is C.