Option C is the correct answer.
Epigenetic tags continue to accumulate in response to ongoing experience throughout the life span.
Epigenetic tags refers to the external modifications to DNA which can turn on and turn off the genes. Though these modifications do not change the DNA sequence but they affect how a cell reads the genes.
Base on the data and the finding I conclude that Nitrates can lower oxygen level in the water and because of it, the fish were killed and also the small fish could be poisoned. I hope you are satisfied with my answer and feel free to ask for more clarification. Have a nice day
