At a distance of 25 kilometers from the coast, phytoplankton cells have an average diameter of option A: 650 micrometers.
The average diameter of a phytoplankton cell is 650 micrometers, and since we know that the diameter of a phytoplankton cell is 900 micrometers, a decrease in diameter of 250 micrometers occurs every 25 kilometers. This decrease occurs at a rate of about 50 micrometers every 5 kilometers.
So, if we subtract this 250 micrometers from 900 micrometers, we get 650 micrometers. So, at a distance of 25 kilometers from the seashore, the mean diameter of a phytoplankton cell is 650 micrometers.
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