Last vertebrae of a frog are:
A. Paracholic
B. Amphicoelous
C. Opisthocoelous
D. Urostyle

Hint: Vertebral column of a frog is made up of 10 free vertebrae. Different species of frogs have a different number of columns. The frog has vertebrae similar to that of humans. Frogs are cold-blooded which means that they can change their body temperature based on the environment.

Complete Answer:
- As we know frogs are members of the amphibian group and its scientific name is Anura. It can survive in water as well as land. Frogs have bulging and big eyes. Hind feet are webbed which is adapted for jumping which helps in the movement of frogs.
- Several varieties of frogs are found in different habitats such as lakes, ponds, forests, freshwater and saline water, etc. The average lifespan of a frog is about 10-12 years. The important thing to note here is that Frogs are classified in phylum-Chordata and Subphylum-Vertebrata Limbs of anurans (frogs) are odd compared to other tetrapods (other amphibians and reptiles).
- Now we will understand that amphibians include a bony skeleton and usually have four limbs. The skin is moist and thin with no scales on the body. The vertebral column of frogs contains 10 free vertebrae and one fused bone called urostyle. It is otherwise called a coccyx. Frogs usually have shorter vertebral arrangements with the tailbone urostyle. This mainly forms the posterior part of the vertebral arrangements of frogs.
- It is a cylindrical rod-like central unit present in the pelvis. This urostyle tailbone is made of ilia and dorsal ridges. The nature of the urostyle is determined by the dorsal ridges present in the urostyle. It may be smooth or unsmooth thicker with ridges. This is responsible for the hopping movement of the frogs.

Hence option D is the correct option for the above question.

Note: Generally organisms can be classified as vertebrates and invertebrates. The vertebral column is the determining feature of the vertebrates. Frog is an organism that has a different tailbone in the vertebral column which supports its movements. This reduced vertebral column is the main reason to maintain the posture and jumping movement of the frog.