Consider the rectangular strip of length 12 below, divided into three rectangles. The distance between the centers of two of the rectangles is 4. What is the length of the other rectangle?[asy]
size(120);
draw((0,0)--(12,0)--(12,1)--(0,1)--cycle);
draw((8,1)--(8,0));
draw((3,1)--(3,0));
dot((1.5,0.5));
dot((5.5,0.5));
draw((1.5,0.5)--(5.5,0.5));
[/asy]<spanclass=′latex−bold′>(A)</span>2.5<spanclass=′latex−bold′>(B)</span>3<spanclass=′latex−bold′>(C)</span>3.5<spanclass=′latex−bold′>(D)</span>4<spanclass=′latex−bold′>(E)</span>4.5