Which soil horizon contains the finest particles and the most humus?

1. A soil profile is made of layers called horizons, each with its own composition. 2. The A horizon is the topsoil, holding the finest particles and the greatest amount of humus. 3. That humus content is what makes it the most fertile layer for plant growth. 4. The C horizon is bedrock and the D horizon holds small soil particles beneath it. 5. There is no E horizon in the soil profile at all, so any option naming one is wrong on its face. _Source: NECTA CSEE 2023 Geography 013, Question 1: Multiple Choice Questions, item (ii)_