Task: Class Definition Understanding (ontology: Earth_Environment/EnvironmentOntology)

Which of the following definitions best describes 'compound organ'?

A. Anatomical structure that has as its parts two or more multi-tissue structures of at least two different types and which through specific morphogenetic processes forms a single distinct structural unit demarcated by bona fide boundaries from other distinct anatomical structures of different types.
B. Organ consisting of skeletal tissue. Encompasses whole bones, fused bones, cartilaginious elements, teeth, dermal denticles.
C. Anatomical surface structure found in many aquatic organisms. It is a respiration organ whose function is the extraction of oxygen from water and the excretion of carbon dioxide. The microscopic structure of a the concept is such that it presents a very large surface area to the external environment. Gills usually consist of thin filaments of tissue, branches, or slender tufted processes which have a highly folded surface to increase surface area. A high surface area is crucial to the gas exchange of aquatic organisms as water contains only 1/20 parts dissolved Oxygen compared to air. With the exception of some aquatic insects, the filaments and lamellae (folds) contain blood or coelomic fluid, from which gases are exchanged through the thin walls. Oxygen is carried by the blood to other parts of the body. Carbon dioxide passes from the blood through the thin the concept tissue into the water. Gills or the concept-like organs, located in different parts of the body, are found in various groups of aquatic animals, including mollusks, crustaceans, insects, fish, and amphibians.
D. An organ that is capable of transducing sensory stimulus to the nervous system.

Answer: Anatomical structure that has as its parts two or more multi-tissue structures of at least two different types and which through specific morphogenetic processes forms a single distinct structural unit demarcated by bona fide boundaries from other distinct anatomical structures of different types.