Which choice completes the text with the most logical transition?

The text begins by explaining that biologists typically assess oyster reef health by measuring shell growth and density. The second sentence reveals a critical limitation of this approach: high growth rates can occur in polluted waters, thereby masking underlying physiological damage. The final sentence asserts that accurately evaluating reef resilience requires testing biochemical markers rather than relying solely on growth metrics. Because this shift in methodology is a direct consequence of the diagnostic vulnerability identified in the second sentence, a cause-and-effect transition such as "Accordingly" is required.

Choice A is incorrect because "In contrast" falsely presents the sentence as a simple antithesis to the previous statement; while the two testing methods differ, the final sentence is an actionable conclusion drawn from the limitation explained previously, not a direct coordinate contrast.

Choice C is incorrect because "For instance" suggests that the final sentence provides an illustrative example of the conventional metrics described in the passage, whereas it actually proposes a necessary corrective approach.

Choice D is incorrect because "Furthermore" treats the final sentence as an additive or supplementary point rather than a direct logical deduction based on the flaw described in the second sentence.