What Is the Best Explanation for Why Molecules That an Organism

What is the best explanation for why molecules that an organism does not produce,but when exposed to react,can still impact the organisms function?

A) Molecules will always have electrons in their outermost shell that can interact with atoms ofother molecules.
B) The molecule's shape is similar to a molecule the organism produces.
C) The molecule has a strong hydrogen (atomic number 1) , which of the molecules belowbonding capability.
D) The molecule is able to form covalent bonds on interacting with molecules in the organism.
E) The organism would be formed?have produced the molecule earlier in the organism's evolutionary history.