In Hydra, absence of circulatory system is compensated by

• A. Gastrovascular cavity
• B. Tentacles
• C. Pseudocoelomic fluid
• D. Mesoglea

In Hydra, the absence of a circulatory system is compensated by the presence of a gastrovascular cavity. This cavity serves multiple functions, including digestion and the distribution of nutrients throughout the organism's body. It allows for the exchange of gases and nutrients directly with the surrounding environment, making it an essential feature for Hydra's survival.

Key Features of the Gastrovascular Cavity

• Digestion: Food is broken down and absorbed here.
• Nutrient Distribution: Nutrients are transported to cells directly.
• Gas Exchange: Oxygen and carbon dioxide are exchanged with the environment.

Other options like tentacles, pseudocoelomic fluid, and mesoglea play different roles in Hydra's biology but do not replace the need for a circulatory system in the same way as the gastrovascular cavity does.