2. A. The value of $\frac{1^{2}-3^{2}+5^{2}-7^{2}+\cdots+97^{2}-99^{2}}{1-3+5-7+\cdots+97-99}$ is ( ).
(A) 1
(B) 50
(C) 100
(D) 2500
2. A. C.

Original expression
$$
\begin{array}{l}
=\frac{(-2) \times(1+3)+(-2) \times(5+7)+\cdots+(-2) \times(97+99)}{(-2)+(-2)+\cdots+(-2)} \\
=\frac{1+3+5+7+\cdots+97+99}{25}=100 .
\end{array}
$$