These animals have three germinal layers but no coelom

Explanation

Option A: Flatworms, also known as Platyhelminthes, have three germinal layers (ectoderm, mesoderm, and endoderm) but do not possess a true coelom. They have a solid body structure without a fluid-filled body cavity. Instead, they have a parenchyma, which is a loose tissue that fills the space between organs.Option B: Roundworms, also known as Nematodes, are another group of animals that have three germinal layers but lack a true coelom. They have an inner tube-like digestive tract but lack a fully developed body cavity. Instead, they possess a pseudocoelom, which is a partially lined body cavity.Option C: Cnidarians, such as jellyfish, corals, and sea anemones, have three germinal layers but do not have a coelom. They have a sac-like body plan with a central digestive cavity called the gastrovascular cavity. The gastrovascular cavity serves both as a digestive and circulatory system, but it is not considered a true coelom.Option D: Chordates, which include vertebrates (animals with a backbone) and some invertebrates, have three germinal layers and possess a true coelom. Chordates have a well-developed body cavity that is fully lined by mesoderm. Examples of chordates include mammals, birds, reptiles, amphibians, and fish.