Answer: c. 25.50%
Soil porosity refers to the amount of pores, or open spaces present between the soil particles. Soil porosity is an important property of soil. It allows the absorption of water and air through the particles of soil. The loose soil will have separated particles of soil hence, will have high porosity. The dense and compact soil particles will have less porosity because compaction decreases the pores inside the soil. Sand is a soil which has particles finer than gravel and coarser than silt. The particles of sand remains loose hence, it will exhibit particles of small grain size with low porosity and high drainage. Therefore, the porosity of sand sample is 25.50%.