Correct option is A
✅ (a) 10:1: • C:N (Carbon to Nitrogen) ratio in most normal agricultural soils is around 10:1. • This means for every 10 parts of carbon, there is 1 part nitrogen. • Ideal for balanced microbial activity and organic matter decomposition.
❌ (b) 15:1 and above: • Such higher C:N ratios slow down decomposition, common in raw organic matter like straw.