Let ∠ABC=24∘ and ∠ABD=20∘. What is the smallest possible degree measure for ∠CBD?<spanclass=′latex−bold′>(A)</span>0<spanclass=′latex−bold′>(B)</span>2<spanclass=′latex−bold′>(C)</span>4<spanclass=′latex−bold′>(D)</span>6<spanclass=′latex−bold′>(E)</span>12