If inequality \frac {\sin ^{3} x}{\cos x} \plus{} \frac {\cos ^{3} x}{\sin x} \ge k is hold for every x∈(0,2π), what is the largest possible value of k?<spanclass=′latex−bold′>(A)</span>21<spanclass=′latex−bold′>(B)</span>43<spanclass=′latex−bold′>(C)</span>1<spanclass=′latex−bold′>(D)</span>23<spanclass=′latex−bold′>(E)</span>None