Sentences of a paragraph are given below in jumbled order. Arrange the sentences in the right order to form a meaningful and coherent paragraph.
A. This invention has helped us to heal wounds caused by bacteria.
B. Penicillin is one of the most useful drugs man has invented.
C. In the beginning however, very few people knew of this discovery and its use.
D. Its use has saved the lives of hundreds of thousands of soldiers.