Viral infections are?

• A. Reproduced inside the human cell
• B. Transmitted by direct contact only
• C. Not contagious
• D. Visible without a microscope

Answer: (A)

Viruses reproduce inside living cells because they are obligate intracellular parasites that lack their own replication machinery. Once a virus enters a host cell, it hijacks the cell’s machinery—ribosomes, enzymes, and energy—to make viral components, assemble new viruses, and then release them to infect more cells. This intracellular replication is what characterizes viral infections.

That’s why the statement about reproduction inside the human cell is the best answer. Other points are incorrect: many viruses are contagious and can spread through airborne, droplet, contact, or vector routes, not just direct contact; viruses are too small to be seen without a powerful microscope, so they aren’t visible to the naked eye.