The outer layer of skin is formed by

Squamous epithelial cells

Explanation: Squamous epithelial cells form the outer layer of skin, but they serve much more than a cosmetic role. Your skin protects against invasion from bacteria and other infectious organisms. Throughout life, you collect a thin film of bacteria on your skin. If these squamous epithelial cells didn’t form a tough barrier, the bacteria would penetrate the skin and invade your body. Disorders in which this barrier is lost—such as in burns—can place an individual at great risk for infection.

a. the production of carbon dioxide through the process of photosynthesis

the answer would be d : p