The correct answer is Integumentary system.
The integumentary system includes skin and all its appendages (hair, scales, feathers, hooves, and nails) with the function to protect the body. It protects body from damage, from loss of water, from abrasion from outside and even protects the deeper tissues. On the other hand, integumentary system excretes wastes, regulates temperature, provides synthesis of vitamin D and many other things.
D. Ligaments are strong and flexible bands of connective tissue that holds bones together meeting at a point known as joints. The first option - tendons - is also a connective tissue but they attach muscle to the bone.
Reactants are the molecules that begin cellular respiration, in this case that would be oxygen<span> and </span>glucose<span>. Hope this helps. </span>