Which characteristic is shared by cnidarians and flatworms?

• A. Presence of a gastrovascular cavity
• B. Possession of a true coelom
• C. Body covered with choanocytes
• D. Radial symmetry in all life stages

Answer: (A)

Verified step by step guidance

1. Understand the key characteristics of cnidarians: Cnidarians are simple animals that include jellyfish, corals, and sea anemones. They have a gastrovascular cavity, which is a single opening that serves as both mouth and anus, and they exhibit radial symmetry in their polyp or medusa stages.
2. Understand the key characteristics of flatworms: Flatworms are a group of simple, bilaterally symmetrical animals. They also have a gastrovascular cavity, but they lack a true coelom (body cavity).
3. Eliminate the incorrect options: 'Possession of a true coelom' is incorrect because neither cnidarians nor flatworms have a true coelom. 'Body covered with choanocytes' is incorrect because choanocytes are specific to sponges, not cnidarians or flatworms. 'Radial symmetry in all life stages' is incorrect because flatworms exhibit bilateral symmetry, not radial symmetry.
4. Focus on the shared characteristic: Both cnidarians and flatworms have a gastrovascular cavity, which is a simple digestive system with a single opening.
5. Conclude that the correct answer is 'Presence of a gastrovascular cavity,' as it is the characteristic shared by both cnidarians and flatworms.