For recycling of materials which one is most necessary

One of the following helps in the recycling of materials in an ecosystem. This one is :

Where do you find these recycling codes of materials which are made from plastics?

Assertion : Recycling of materials is must for the maintenance of biosphere . Reason : Because energy flows unidirctionally in a food chain.

Does your village or nearest city has a recycling unit of waste materials? Write in detail the steps involved in it.

Which one is a nano material