Let AB be a segment of length 26, and let points C and D be located on AB such that AC=1 and AD=8. Let E and F be points on one of the semicircles with diameter AB for which EC and FD are perpendicular to AB. Find EF.<spanclass=′latex−bold′>(A)</span>5<spanclass=′latex−bold′>(B)</span>52<spanclass=′latex−bold′>(C)</span>7<spanclass=′latex−bold′>(D)</span>72<spanclass=′latex−bold′>(E)</span>12