Are viruses alive? this question is debated among scientists throughout the world. scientific researchers discovered agents that behaved like bacteria, causing diseases such as rabies and hoof-and-mouth, but were much smaller. at this time it became the general view that viruses were biologically "alive." this perception changed in 1935 when the tobacco mosaic virus was crystallized, and scientists demonstrated that the particles lacked any mechanisms necessary for metabolic function. it was determined that viruses consisted of a nucleic acid, dna or rna, surrounded by a protein shell. the scientific view changed: viruses are complex biochemical mechanisms but are not alive. viruses exist in two distinct states. when not in contact with a host cell, the virus remains entirely dormant. during this time there are no biological activities occurring and the virus is nothing more than a static organic particle. in this simple, clearly non-living state viruses can remain for extended periods of time, waiting to come into contact with the appropriate host. when the virus comes into contact with the appropriate host, it becomes active, reacts to its environment and/or host and directs its efforts toward self-replication. the viral goal now is to produce more viruses to attack host cells. which of these choices provides a direct refutation of an argument found in this passage, that viruses are not living organisms? a) since living things reproduce, and viruses reproduce, they must be alive. b) many bacteria become spores, highly protected inanimate forms, during times of stress. c) a baby can't survive without , just like a virus needs a host in order to reproduce. d) before changing into a butterfly, caterpillars go through a cocoon stage where they appear dormant.