Where Does Antivenom Come From

Where does antivenom come from?

A) It is extracted directly from the snake.
B) It is engineered in the lab based on the particular toxin involved.
C) Small amounts of venom is injected into animals which then produce antibodies, and those antibodies are collected and concentrated into antivenom.
D) Small amounts of venom is injected into animals their thymus is then extracted and ground up to release the B and T memory cells that can then be used as antivenom.
E) Snakes are allowed to bite mice, and the memory cells from the mice are then collected and concentrated into antivenom.