Concept:Clayey soil has poor drainage and low aeration, so improving its physical condition is key to increasing crop yield.
Explanation:Clayey soil is heavy, sticky when wet, and drains water very slowly.
Adding humus improves the soil structure by creating spaces for air and water movement.
Adding lime helps reduce soil acidity and causes clay particles to clump together, allowing better drainage and root penetration.
Adding more water would worsen waterlogging and reduce oxygen in the soil.
Fertilizers or weedicides add nutrients or control weeds, but they do not correct the poor physical condition of clayey soil.
Therefore, the best combination is lime to adjust pH and improve soil structure, along with humus to enhance fertility and aeration.
Answer:B. lime and humus