A major chemical spill occurred five years ago at Baker’s Beach, the

GMATNinja can you help with an explanation? I'm struggling to see why (D) is incorrect. I felt it offered a different explanation that would weaken the argument if true. Thanks in advance!

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Understanding the argument -
A major chemical spill occurred five years ago at Baker’s Beach, the world’s sole nesting ground for Merrick sea turtles, and prevented nearly all the eggs laid that year from hatching. Fact
Yet the number of adult female Merricks returning to lay their eggs at Baker’s Beach has actually increased somewhat since five years ago. "Yet" introduces the contrast, and this is a Fact.
Clearly, environmentalists’ prediction that the world’s Merrick population would decline as a result of the spill has proven unfounded. - Conclusion. "environmentalists’ prediction has proven unfounded"

Option Elimination - Weaken the conclusion.

A. The chemical spill five years ago occurred at a time when there were neither Merrick sea turtles nor Merrick sea turtle eggs on Baker’s Beach. - Facts respected. The argument clearly says the spill "prevented nearly all the eggs laid that year from hatching." Challenging the facts is not the scope of GMAT arguments.

B. Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs when they are ten years old. - ok. So, those impacted five years ago will show the results/come back, if any, five years from now.

C. Under normal conditions, only a small proportion of hatchling female Merrick sea turtles survive in the ocean until adulthood and return to lay their eggs at Baker’s Beach. Are we saying that with the chemical spill, more sea turtles survive somehow? At best, it's the opposite of what we need.

D. Environmental pressures unrelated to the chemical spill have caused a significant decline in the population of one of the several species of sea birds that prey on Merrick sea turtle eggs. - It's going in a direction that the population of sea turtles may increase. But wait, the scope of our argument is to weaken the conclusion, which is "environmentalists’ prediction that the world’s Merrick population would decline as a result of the spill has proven unfounded." So, we are primarily concerned about the chemical spill and its effect on sea turtles. This option talks about some other variable that is not even in the scope of the argument. Out of scope.

E. After the chemical spill, an environmental group rejected a proposal to increase the Merrick sea turtle population by transferring eggs from Baker’s Beach to nearby beaches that had not been affected by the spill. - out of scope.