Reena segregates the waste at home and put the bio degradable waste in a pot containing soil. She leaves it for 15 days and uses that soil for her plants in the garden. Why do you think she did so?

Reena is making compost to reuse or recycle biodegradable waste and convert it into a natural fertilizer.

Explanation:

By placing the biodegradable matter in the pot with soil, microorganisms living in that soil are able to decompose the wastes and produce fertile products. This fertilized soil is very useful in plant care because it provides many nutrients and benefits for needed the plants' growth.

Compost consists of a controlled oxidation biological process and microorganisms and other invertebrates such as earthworms are in charge of decomposition of the solid matter. The product is used as a natural fertilizer and is a good substitute for chemical fertilizers. When composting, temperature, and humidity must be controlled. The process lasts one week or two until the whole solid wastes are degraded and mixed with the rest of the soil.    

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.