Answer:
The correct options are B and C
Step-by-step explanation:
Option A is false because bacteria fix nitrogen by converting it into ammonia. The ammonia is used by the plants for different functions like development etc.
Option B is correct because plants can take up both ammonium ions and nitrate ions from the soil. They use these ions to make amino acids which are required by the plant for different activities.
Option C is correct because nitrifying bacteria are the bacteria which convert ammonia into nitrites and then nitrates in a process which is termed as nitrification.
Option D is false because herbivores eat plants to make amino acids and proteins.