_ are tetrapods.
Options:
- (A) animals
- (B) amoeba
- (C) Frogs
- (D) Length
- (E) insects
- (F) Spiders
- (G) Snakes
- (H) Birds OK. Let's think hard:
Amphibians are the first true tetrapods, or vertebrates with four limbs. Frogs are classified as amphibians. Frogs are tetrapods.
So, the final answer is (C).