Preparation of FYM by Trench Method is given by

Answer: Option A

FYM is farm yard manure, which is an important organic resource for agricultural production, including compost, cow dung, green manure, etc.
Preparation of FYM (Farmyard manure) by Trench method is given by C. N. Acharya.
In this method trenches of 6 - 8 m in length, 1.5 - 2 m in width, and 1 - 1.25 m in depth are prepared. A mixture of dung and urine-soaked litter is deposited in layers in these trenches until it becomes 50 cm above the ground layer. It is then watered carefully and mud plastered. The FYM is ready in about 6 months.