Foramen transversarium, also known as vertebrarterial canal, is present in:
The correct answer is option 'A' - Cervical vertebrae.

Explanation:
The foramen transversarium, also referred to as the vertebrarterial canal, is a unique feature found only in the cervical vertebrae. Let's understand this in more detail:

Cervical vertebrae:
- The cervical vertebrae are the seven vertebrae that make up the neck region of the vertebral column.
- They are labeled as C1 to C7, with C1 being the atlas and C7 being the vertebra prominens.
- The cervical vertebrae have several distinguishing features, including the foramen transversarium.

Foramen transversarium:
- The foramen transversarium is an opening that is present on both sides of the cervical vertebrae, except for the atlas (C1) and axis (C2).
- These openings are located in the transverse processes, which are bony projections that extend laterally from the vertebrae.
- The foramen transversarium serves as a passageway for the vertebral artery, vein, and sympathetic nerves.
- The vertebral artery is an important blood vessel that supplies the brain, and it passes through the foramen transversarium of the cervical vertebrae before entering the skull.

Significance:
- The presence of the foramen transversarium in the cervical vertebrae allows for the protection and passage of the vertebral artery, which supplies blood to the brain.
- The vertebral artery is a major contributor to the blood supply of the brain, and any obstruction or damage to it can lead to serious neurological consequences.
- The foramen transversarium provides a unique anatomical feature specific to the cervical vertebrae that distinguishes them from the vertebrae in other regions of the spine.

Therefore, the correct answer is option 'A' - Cervical vertebrae.