Calculation of rainfall volume:
Rainfall depth \(d = 1\text{ cm} = 0.01\text{ m} = 10^{-2}\text{ m}\). Catchment area \(A = 1\text{ km}^2 = (1000\text{ m})^2 = 10^6\text{ m}^2\).
Volume of water \(V = A \times d = 10^6\text{ m}^2 \times 10^{-2}\text{ m} = 10^4\text{ m}^3\) (or 1 hectare-meter = 10,000 \(\text{m}^3\)).

NRCS (USDA-SCS) Hydrologic Soil Groups classification:
Group A: Deep sand or gravel; very high infiltration rate ($\gt 0.75\text{ cm/h}$); low runoff potential (Statement A is false, B is true).
Group B: Moderately deep to deep, moderately fine to moderately coarse textures (loam/silt loam); moderate infiltration rate ($0.38 - 0.75\text{ cm/h}$); moderately low runoff potential (Statement D is false).
Group C: Soils with impeding layer or moderately fine/fine texture (clay loams); slow/low infiltration rate ($0.13 - 0.38\text{ cm/h}$); moderately high runoff potential (Statement C is true).
Group D: Heavy clays with high swelling, high water table, or shallow over impervious layer; very low infiltration rate ($\lt 0.13\text{ cm/h}$); high runoff potential (Statement E is false).