The correct answer is A. Collagen.
Collagen is a protein that is the main structural component of skin, bones, and connective tissues. It is a fibrous protein that is made up of long chains of amino acids. Collagen is responsible for the strength and elasticity of skin and other tissues.
Carbohydrates are a type of molecule that is made up of carbon, hydrogen, and oxygen atoms. They are the main source of energy for the body. Carbohydrates are found in foods such as bread, pasta, rice, and potatoes.
Polymers are large molecules that are made up of repeating units of smaller molecules. They are found in a variety of materials, including plastics, rubber, and nylon.
Nucleic acids are molecules that are responsible for storing and transmitting genetic information. They are found in the nucleus of cells.
In conclusion, the major ingredient of leather is collagen. Collagen is a protein that is the main structural component of skin, bones, and connective tissues. It is a fibrous protein that is made up of long chains of amino acids. Collagen is responsible for the strength and elasticity of skin and other tissues.