Question

read the opinion below.
swamps should be protected and valued.
select the reason that best supports this opinion.
the everglades is a freshwater swamp and national park in florida.
swamps do an excellent job of cleaning an areas water supply.
many dangerous creatures, such as alligators and poisonous snakes, live in swamps.

Explanation:

The opinion is that swamps should be protected and valued. The first option just states a fact about a swamp (The Everglades) being a national park but doesn't explain why swamps in general should be protected. The third option mentions dangerous creatures in swamps, which is more of a reason one might be cautious around swamps rather than a reason to protect them. The second option, "Swamps do an excellent job of cleaning an area's water supply", provides a positive ecological function (water - cleaning) that gives a valid reason for protecting and valuing swamps.

Answer:

"Swamps do an excellent job of cleaning an area's water supply."