The first electron micrograph of a virus (tobacco mosaic virus) was produced in 1939. before that time, how did scientists know that viruses existed if they could not see them? (hint: early scientists called viruses "filterable agents.")

maritime tropical may be your answer.

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation:

frogs. the lower the ph the higher the acid content. frogs have the highest tolerance in this scenario.