Difficulty: Medium
Correct Answer: if only conclusion II follows
Explanation:
Introduction / Context:
The stem states an observed environmental trend: the Antarctic ozone hole is shrinking. Two conclusions are offered about chlorofluorocarbons (CFCs): (I) removal now exceeds new releases; (II) atmospheric levels of destructive CFCs are declining. We must identify the inference supported by the report without adding stronger claims.
Given Data / Assumptions:
Concept / Approach:
A shrinking hole is consistent with falling concentrations of ozone-depleting substances (ODS) like CFCs. However, claiming that natural/atmospheric removal outpaces total releases (I) is a stronger, quantitative dynamic not stated in the stem.
Step-by-Step Solution:
Verification / Alternative check:
The hole could shrink due to lower emissions plus slow stratospheric cleansing; we are not told the current balance is removal > release in all regions/times. Thus II, not I, follows.
Why Other Options Are Wrong:
Common Pitfalls:
Conflating “improving indicator” with a specific quantitative mechanistic claim.
Final Answer:
if only conclusion II follows
Discussion & Comments