Correct Option: A

Proteins are very important for children as they help their body grow. Proteins are the source of amino acids, which are the building blocks of your child’s body. Amino acids help the development of muscle, bones, skin and various organs in children. The enzymes which are catalysts of body growth are proteins produced by the body. As children grow, their immune system also keeps improving and maturing. Proteins also play an important role in the working and development of the immune system. Many hormones which are important to regulate the behaviour of various body functions, are also proteins. For example, insulin is a protein.