Chemicals used in pesticides have adverse effects on nature. Comment

can harm nature, animals, habitats, etc

Explanation:

Alongside killing weeds it can hurt/kill, insects, non targeted plants, animals (esp. animals that eat the damaged plants.) and birds. It can cause soil pollution and can seep and pollute the ground water which can't be drunken if polluted. If it is it can harm/kill animals and humans.

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

i think that c)gold was found there

but i am not sure