The original virus was avian sarcoma. That is option B.
Peyton Rous was a pathologist that worked on the transfusion of materials from the tumour of an affected chicken to a healthy one.
He discovered that the healthy chicken developed cancer after a while due to the transfusion process.
The filterable agent was later called Rous sarcoma virus (RSV) which is an avian sarcoma virus.
This formed the basis for the understanding of the infection process of Human immunodeficiency virus because they too where able to cause skin cancer called Kaposi sarcoma.
Learn more about viruses here:
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