As newts' poison became more toxic, the garter snake's resistance to it became more efficient. This is an example of convergent evolution
coevolution
divergent evolution
adaptive radiation

coevolution

Explanation:

As newts' poison became more toxic, the garter snake's resistance to it became more efficient. This is an example of coevolution.

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."