Which animal can be classified as a tetrapod (a vertebrate lineage characterized by having four limbs or being descended from a four-limbed ancestor)?

• A. Shark
• B. Jellyfish
• C. Salmon
• D. Frog

Answer: (D)

Verified step by step guidance

1. Understand the definition of a tetrapod: a vertebrate animal that either has four limbs or is descended from an ancestor with four limbs.
2. Identify the key characteristic of tetrapods, which is the presence of four limbs or limb-like structures.
3. Examine each animal option to determine if it fits the tetrapod criteria:
4. - Shark: a cartilaginous fish with fins, not limbs, so it is not a tetrapod.
5. - Jellyfish: an invertebrate with no backbone or limbs, so it is not a tetrapod.
6. - Salmon: a bony fish with fins, not limbs, so it is not a tetrapod.
7. - Frog: an amphibian with four limbs, directly fitting the tetrapod definition.