The virus was first discovered by:

Explanation

The discovery of viruses dates back to the late 19th century, when scientists were investigating diseases in plants that could not be explained by known bacteria. In 1892, Russian scientist Dmitri Ivanovsky first identified the existence of a new type of infectious agent while studying tobacco mosaic disease. He found that the disease could be transmitted by sap from infected plants, even after the sap was passed through a porcelain filter fine enough to remove all known bacteria. Later, in 1898, Dutch microbiologist Martinus Beijerinck confirmed Ivanovsky's findings and described the agent as a "contagium vivum fluidum" (a contagious living fluid), coining the concept of a virus as something fundamentally different from bacteria. This discovery marked the beginning of virology, the study of viruses, and laid the foundation for understanding these unique infectious agents.