The main structure in vertebrates that supports and protects the body is the

Step 1: Analyze the question The question asks for the main structure in vertebrates that does two jobs: supports the body and protects it (especially delicate organs).

Step 2: Explain the concept Vertebrates (fish, amphibians, reptiles, birds, mammals) have an internal skeleton called an endoskeleton, made of bone and/or cartilage. Its main functions are:

• Support: it gives the body shape and holds it upright.
• Protection: the skull protects the brain, the rib cage protects the heart and lungs, and the vertebral column protects the spinal cord.
• Movement: bones act as levers for muscles.
• Other roles: blood cell production in bone marrow and mineral storage.

Step 3: Evaluate each option

• A. Skeleton: It supports and protects the body. ✔
• B. Ligament: It connects bone to bone at joints, so it provides stability but does not protect organs.
• C. Muscle: It produces movement by contracting. It does not provide the main support or protection.
• D. Joint: It is the place where two bones meet, allowing movement. It is not a protective structure.

Step 4: Answer The correct answer is A. skeleton.

Exam tip: Match the function to the structure:

• Support + protection → skeleton
• Movement → muscle
• Bone-to-bone connection → ligament
• Muscle-to-bone connection → tendon
• Where bones meet → joint