Which biological organism having highest influence on soil aggregate formation?

Answer: Option C

Plant's roots are biological organisms having the highest influence on soil aggregate formation.
Plant roots play a vital role in aggregate formation by secreting organic compounds called root exudates. These helps bind soil together near the root zone.
However, Soil aggregates are clumps of soil particles that are held together by moist clay, organic matter (like roots), gums (from bacteria and fungi) and fungal hyphae.