(A) Keratin

Hair is primarily composed of a protein called keratin. Keratin is a fibrous structural protein that forms the main component of hair, as well as nails and the outer layer of the skin. It provides strength and resilience to these structures. The other options—Casein, Globulin, and Mucin—are proteins found in other parts of the body and have different functions.

(A) Guava

Guava is considered one of the richest sources of vitamin C among fruits. It contains a high concentration of ascorbic acid, which is a form of vitamin C. While other fruits like oranges and pineapples also contain vitamin C, guava surpasses them in terms of vitamin C content per serving. Tomatoes, although a good source of vitamin C, are generally lower in vitamin C compared to guava.