Here's a problem to solve: When fresh water and salt water meet in an estuary, the salt water typically flows underneath the fresh water because the salt water is denser. What effect does this most likely have on the nutrients concentrated in the fresh water?

Among the 4 following options, which is the correct answer?

- A: They are kept close to the shore.
 
- B: They are spread out from the shore.
 
- C: They are diluted by the ocean water.
 
- D: They are inactivated by the ocean water.
 