4. Let $s=\frac{1}{(1+x)^{2}}+\frac{1}{(1-x)^{2}}$. Then, the relationship between $s$ and 2 is ( ).
(A) $s=2$
(B) $s<2$
(C) $s>2$
(D) The relationship between $s$ and 2 depends on the value of $x$
4.D

Translate the text above into English, please retain the original text's line breaks and format, and output the translation result directly.