Concept:Hydrophytes like water lily need special air-filled tissues to stay afloat.Explanation:Water lily is a freshwater plant that lives on the surface of water.Buoyancy is the upward force that pushes the plant upward in water.Aerenchyma tissues contain large air spaces.These air spaces trap air and make the plant light.This helps the water lily float easily on water.Therefore, the possession of aerenchyma tissues solves the problem of buoyancy.Answer:A. aerenchyma tissues