Hello There!
Before viruses can reproduce, they must infect a host cell.
Viruses need a way to enter the body before they can infect a host cell.
Explanation:
1. they are convenient to use 2. it helps the international tade 3. it eases the exchange of material
I recommend reading a passage about it. Hope this helps!
B, C, D, B
I hope these are right, hope this helped.
