Concept:When each dimension is increased by 100%, the new dimensions become twice the original dimensions.Explanation:Let the original length and breadth be L and B.Original area is L×B.After a 100% increase, new length =L+L=2L.New breadth =B+B=2B.New area is 2L×2B=4LB.Increase in area is 4LB−LB=3LB.Percentage increase is LB3LB​×100=300%.Answer:C. 300%