The correct option is A M.W. Beijerinck
Dmitri Ivanovsky used one of these filters to show that sap from a diseased tobacco plant remained infectious to healthy tobacco plants despite having been filtered.
Beijerinek (1898) demonstrated that the extract of the infected plants of tobacco could cause infection in healthy plants and named the new pathogen “virus” and called the fluid Contagium vivum fluidum (infectious living fluid).
W.M. Stanley (1935) showed that viruses could be crystallised as proteins.
In 1971, T.O. Diener discovered viroids.