Answer choice (E) is nearly a Mistaken Negation of what the argument wants. Look at the relation between the premises and the conclusion:
Premises: This would likely help the environment, but also likely reduce economic growth.
Conclusion: We shouldn't do it.
Answer choice (E) is a conditional:
(policy likely protects environment) + (policy unlikely to reduce economic growth)
So if something is likely to protect the environment and unlikely to reduce economic growth, we should do it. But the argument in the stimulus wants us not
to do something because it is
likely to reduce economic growth. It's true that answer choice (E) matches the stimulus when it talks about the likelihood of the policy protecting the environment, but the policy is not unlikely to reduce economic growth. The conditional just does not apply. At best, that conditional tells me when to do something, not when to refrain from something.