Which of the following is a characteristic of epithelial tissue?

Correct Answer: B

Rationale: Epithelial tissue is avascular, lacking blood vessels, and relies on diffusion from underlying connective tissue for nutrients, as seen in the epidermis or gut lining. Vascular or highly vascularized applies to connective tissues like dermis, not epithelium. Nerve endings may penetrate epithelium, but innervation isn't a defining trait avascularity is. This lack of vasculature, ensuring a protective or selective barrier, makes 'b' the correct characteristic.

Correct Answer: C

Rationale: Osteoclasts resorb bone, breaking down matrix via enzymes/acids to release calcium, balancing remodeling. Osteoblasts form bone, osteocytes maintain it, and chondrocytes produce cartilage, not bone resorbers. Osteoclasts' destructive role, per bone physiology, makes 'c' correct.

Correct Answer: D

Rationale: The vertebral column protects the spinal cord (not heart, a), supports the head , and allows movement/flexibility via joints e.g., cervical flexion. Heart protection is rib cage/sternum. All functions apply, per spinal anatomy, making 'd' correct.

Correct Answer: A

Rationale: Five lumbar vertebrae (L1-L5) form the lower back, supporting weight and flexibility. Seven is cervical, twelve is thoracic, three is miscount. Lumbar's count, per spinal anatomy, makes 'a' correct.

Correct Answer: C

Rationale: Synovial joints (e.g., shoulder) allow the most movement flexion, rotation via fluid-filled capsules. Fibrous are immovable (sutures), cartilaginous slightly movable (vertebrae). Synovial's range, per joint types, makes 'c' correct.