Answer:
See explain
Explanation:
I gotchu. First, let's just remove A from the beaker and feed it to a rat. If he lives, the poison is A, if not it's still in one of the 3. Now, remove B and feed to a rat. If he dies, it's not B or A . . . so on until you have your answer.
I believe it is C and D! ☺️
The answer would be biotic factors because they are living organisms
