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A: An increase in pollution could lead to a decrease in genetic variation in a population of tuna.
An environmental factor that could lead to a decrease in the genetic variation of tuna would be an increase in pollution.
Environmental factors and genetic variability
Environmental factors that lead to a loss of species also cause a decrease in genetic variability.
When a member of a population dies, some genetic variation is lost.
Pollution is a factor that can lead to the loss of individuals or a decrease in the reproductive capability of individuals in a population.
More on genetic variability can be found here: https://brainly.com/question/13952713