The diagram below shows a square of area 36 separated into two rectangles and a smaller square. One of the rectangles has an area of 12. What is the smallest rectangle's area?[asy]
size(70);
draw((0,0)--(2,0)--(2,6)--(0,6)--cycle);
draw((2,2)--(6,2)--(6,6)--(2,6)--cycle);
draw((2,2)--(6,2)--(6,0)--(2,0)--cycle);
label("12",(1,3));
label("?",(4,4));
label("?",(4,1));
[/asy]<spanclass=′latex−bold′>(A)</span>8<spanclass=′latex−bold′>(B)</span>9<spanclass=′latex−bold′>(C)</span>12<spanclass=′latex−bold′>(D)</span>16<spanclass=′latex−bold′>(E)</span>Not Enough Information