The correct option is D 3 - 2 - 1
When spoiled vegetables and fruit waste are mixed with soil, they form a mixture known as compost.
At first, items that cannot decay (e.g. plastic, glass, rubber, etc) are removed from garbage. Only spoiled vegetables, tree leaves, fruit waste and other decayble items are used.
It is mixed with soil properly.
Then, mixture is kept in container for few days. The mixture will turn into compost after it decays.