It will eventually cause the grass to stop growing. It will prevent bacteria from invading the lawn. It will provide the lawn with needed nutrients. It will reduce the insect population.
I gave my students this multiple choice question: Mr. Harris mows his lawn twice each month. He claims that it is better to leave the clippings on the ground. Which long term effect will this most likely have on his lawn?

Only one answer is correct among these 4 choices:
- It will eventually cause the grass to stop growing.
- It will prevent bacteria from invading the lawn.
- It will provide the lawn with needed nutrients.
- It will reduce the insect population.

Could you tell me which one is correct?

It will provide the lawn with needed nutrients.