Final answer:
The process where two related viruses infect the same cell and can produce new viral strains is most closely associated with 'viral coexistence'. This viral reassortment leads to genetic variations that may result in a virus capable of crossing species barriers and possibly causing epidemics.
Step-by-step explanation:
The process by which two related viruses infect the same host at the same time and can lead to the emergence of new viral strains is known as viral reassortment. This phenomenon is not explicitly listed in the provided options, but it closely resembles the concept of 'viral coexistence', which may be the most suitable choice from the given alternatives. During this process, if the two viruses infect the same cell, they can mix and match their genetic material, especially if they are similar types of viruses (like two influenza viruses). This genetic exchange can produce a new virus strain with a unique combination of surface proteins, which may allow it to infect new host species or evade the immune system in ways the original strains could not.
For a new virus to emerge and spread, certain requirements must be met. These include exposure to the virus, following which the virus must adhere to a host cell, eventually leading to invasion and infection of the host. In settings where animals and people are in close contact, such as on farms, a virus can jump the species barrier and, if it has favorable new binding properties, it can spread swiftly. Therefore, continuous monitoring of emerging viruses is essential to prevent global epidemics.