vital organs are protected from harm by a. muscles b.bones c.tendons d.ligaments

Correct answer is b . 

Protects and supports organs: Your skull shields your brain, your ribs protect your heart and lungs, and your backbone protects your spine. Bones also protect the body's organs. The skull protects the brain and forms the shape of the face. The spinal cord, a pathway for messages between the brain and the body, is protected by the backbone, or spinal column. The ribs form a cage that shelters the heart and lungs , and the pelvis helps protect the bladder, part of the intestines, and in women, the reproductive organ. 

Bones are made up of a framework of a protein called collagen  with a mineral called calcium phosphate that makes the framework hard and strong. Bones store calcium and release some into the bloodstream when it's needed by other parts of the body. The amounts of some vitamins and minerals that you eat, especially vitamin D and calcium, directly affect how much calcium is stored in the bones.