Hint: It is a process that occurs inside the living organisms or in a natural setting because the virus doesn’t have their machinery to make copies of themselves. The genetic material is injected by the viruses into the fossils for their own use.
Due to the obligate intracellular pathogens, viruses are not able to replicate without the machinery and metabolism of a host cell. The life cycle of a virus is variable between different species and different categories of the virus. There are six basic stages of viral replication.
1)Attachment - on the capsid of phospholipid envelope proteins interacting with the particular receptors lie on the cellular surface of the host cell. The tropism of a virus is determined by it.
2)Penetration - induction of conformational changes in the viral capsid proteins or the lipid envelope is carried out by the attachment to specific receptors which results in the fusion of viral and cellular membranes. Through receptor-mediated endocytosis some DNA viruses can also enter the host cell.
3)Uncoating - the viral genome in a nucleic acid is released when the viral capsid is removed and degraded by viral enzymes on host enzymes.
4)Replication - the transcription or translation process of the viral genome is initiated by the viral genome becomes uncoated. in this stage of viral replication DNA and RNA viruses and the viruses with the opposite nucleic acid, polarity differentiate greatly and results in the de novo synthesis of viral genome and proteins
5)Assembly - after the synthesis, into new virion the viral proteins are packaged with newly replicated viral genome and are ready for the release from the host cell, and this process is known as maturation.
6)Virion release - lysis or budding are the two methods of viral release. The death of the infected host cell is carried out by the lysis and this type of virus known as cytolytic.
A virus that is released from the cell by budding is the envelope virus such as influenza A virus. These do not kill the infected cell and are termed cytopathic viruses.
So, the correct answer is option (A) "In vivo".
Note: The genetic material that is DNA or RNA is injected into the host cell which is utilized by the viruses for their own machinery.
The new DNA or RNA is synthesized by the host cell's RNA Primase, polymerases, free nucleotides, etc. will make up the hundreds or thousands of new viruses.