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. Yet the number of adult female Merricks returning to lay their eggs at Baker's Beach has actually increased somewhat since five years ago. Clearly, environmentalists' prediction that the world's Merrick population would decline as a result of the spill has proven unfounded.

Which of the following, if true, most seriously undermines the argument offered in refutation of the environmentalists' prediction?

【选项】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.