The numeral 47 in base a represents the same number as 74 in base b. Assuming that both bases are positive integers, the least possible value of a+b written as a Roman numeral, is<spanclass=′latex−bold′>(A)</span>XIII<spanclass=′latex−bold′>(B)</span>XV<spanclass=′latex−bold′>(C)</span>XXI<spanclass=′latex−bold′>(D)</span>XXIV<spanclass=′latex−bold′>(E)</span>XVI