Here's a problem to solve: Which statement explains why most salmon leave salt water and return to fresh water?

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

- A: It is a learned behavior that maintains the population.
 
- B: It is a learned behavior that maintains salt concentrations.
 
- C: It is an inherited behavior that maintains the population.
 
- D: It is an inherited behavior that maintains salt concentrations.
 