Critical Reasoning (CR) | Re: It is the lack of a training program for fishermen

It is the lack of a training program for fishermen, and not the change in oceanic oxygen levels, that has caused the decline in fish harvests off the coast of country X over the last five years. Neighboring country Y has experienced the same changes in oceanic oxygen conditions but has actually seen an increase in the number of fish caught off its coast in each of the last five years.

Which of the following, if true, most seriously weakens the argument above?
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