Here's a problem to solve: Water used in a factory is heated to 75 degrees Celsius. It is discharged into a nearby river that has a normal temperature of 20 degrees Celsius. Which should most likely be done to minimize damage to the river?

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

- A: decrease the temperature of the factory water
 
- B: increase the temperature of the river water
 
- C: remove the vegetation from the river
 
- D: add more fish to the river
 