Which of the following is not considered part of the "golden age" of microbiology?

Question

A.First artificial vaccine is developed

B.Gram stain is devised

C, Viruses are defined

D.all of the above

Please do not guess I chose C but i think it was wrong

Answer 1

You’d help yourself if you followed directions and put your SUBJECT in the right place.

Answer 2

http://people.cst.cmich.edu/schul1te/208%20web/208lecture3.htm