in an estuary in an open ocean at an intertidal zone at a hydrothermal vent
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Where is the biological magnification of pollutants most likely to be the greatest?
Possibilities:
- in an estuary
- in an open ocean
- at an intertidal zone
- at a hydrothermal vent

in an estuary