The molecules used to control viruses during the infection of animal cells are **Interferons** (Option A). Interferons are signaling proteins released by host cells in response to viral infections. They play a crucial role in the antiviral defense mechanisms of the immune system, helping to inhibit viral replication and the spread of the virus to neighboring cells.

The other options listed (Antigen, Histone, and Serum) are not molecules specifically used to control viruses during infection but may have other roles in immune responses or cellular processes.