以下哪项为配对<em>X<sup>2</sup></em>检验的计算公式？（）(单选题)<br>.<img align="absmiddle" alt="" src="/lqwvjeImg/fe/fe2499dcd41b87f536f00469a550f215.png"><br>.<img align="absmiddle" alt="" src="/lqwvjeImg/a7/a7a26e9c71163afc62fe0b79d12e991a.png"><br>.<img align="absmiddle" alt="" src="/lqwvjeImg/21/21d0028b2d9d56f81b2bc733cc1d5213.png"><br>.<img align="absmiddle" alt="" src="/lqwvjeImg/08/0873a646447430ee7a94fad2dd008a62.png">