配对设计的四格表资料进行比较时,其无效假设是

A、π[img=~/QImg/2013-10-14-10-49-09/image019.jpg]=π[img=~/QImg/2013-10-14-10-49-09/image025.jpg]
B、μ[img=~/QImg/2013-10-14-10-49-09/image019.jpg]=μ[img=~/QImg/2013-10-14-10-49-09/image025.jpg]
C、π[img=~/QImg/2013-10-14-10-49-09/image019.jpg]≠π[img=~/QImg/2013-10-14-10-49-09/image025.jpg]
D、μ[img=~/QImg/2013-10-14-10-49-09/image019.jpg]≠μ[img=~/QImg/2013-10-14-10-49-09/image025.jpg]
E、b=c