Let r be the number that results when both the base and the exponent of ab are tripled, where a,b>0. If r equals the product of ab and xb where x>0, then x=<spanclass=′latex−bold′>(A)</span>3<spanclass=′latex−bold′>(B)</span>3a2<spanclass=′latex−bold′>(C)</span>27a2<spanclass=′latex−bold′>(D)</span>2a3b<spanclass=′latex−bold′>(E)</span>3a2b