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? ["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.", '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.', "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.", "Female Merrick sea turtles begin returning to Baker's Beach to lay their eggs when they are ten years old."]