I believe the answer is different versions of a gene :)
In this scenario, E.coli is living in our intestines, which means we are providing them with a place to live and nutrients to survive. It is also stated that they help us break down some foods.
so as you can see, we benefit them, and they benefit us.
Based on this, after defining all of your options, you will find your answer.
Phosphorus cycles between living things and the SOIL... Soil is the correct answer
