2. Given real numbers $x 、 a_{1} 、 a_{2} 、 y$ form an arithmetic sequence, $x 、 b_{1} 、 b_{2} 、 y$ form a geometric sequence, the range of $\left(a_{1}+\right.$ $\left.a_{2}\right)^{2} / b_{1} b_{2}$ is ( ).
A. $[4,+\infty)$
B. $(-\infty,-4] \cup[4,+\infty)$
C. $(-\infty, 0] \cup[4,+\infty)$
D. Cannot be determined
2. C.
\(\left(a_{1}+a_{2}\right)=x+y, b_{1} b_{2}=x y\), then \(\frac{(x+y)^{2}}{x y}=\frac{y}{x}+\frac{x}{y}+2=\frac{\left(a_{1}+a_{2}\right)^{2}}{b_{1} b_{2}}\).
Also, \(\left(\frac{y}{x}+\frac{x}{y}\right)^{2}=\frac{y^{2}}{x^{2}}+\frac{x^{2}}{y^{2}}+2 \geqslant 4\), so \(\frac{y}{x}+\frac{x}{y} \geqslant 2\) or \(\frac{y}{x}+\frac{x}{y} \leqslant-2\). Therefore, \(\frac{\left(a_{1}+a_{2}\right)^{2}}{b_{1} b_{2}} \geqslant 4\) or \(\frac{\left(a_{1}+a_{2}\right)^{2}}{b_{1} b_{2}} \leqslant 0\).