Question

acid rain threatens sugar maple trees because:
pollution weakens ecosystems.
over - harvesting reduces populations.
new species compete for resources.
technology stabilizes forests.

Explanation:

Acid rain affects ecosystems by altering soil chemistry, which can weaken plants (like sugar maple trees) and disrupt ecological balance. The option "Pollution weakens ecosystems" directly connects acid rain (a form of pollution) to ecosystem weakening. Over - harvesting relates to resource depletion, new species competing is about inter - species competition, and technology stabilizing forests is about human intervention for conservation—none match the acid rain - ecosystem weakening link as well.

Answer:

The correct option is the one with "Pollution weakens ecosystems." (Assuming the options are in a single - choice format with this as one of the radio - button options, e.g., if it's the second option from the top, we'd identify it as per its position, but from the text, the relevant option is "Pollution weakens ecosystems.")