The correct answer is B. melanin.
Melanin is a pigment that is produced by cells in the skin called melanocytes. It is responsible for the color of our skin, hair, and eyes. Melanin helps to protect our skin from the sun’s harmful ultraviolet (UV) rays. When we are exposed to UV rays, our bodies produce more melanin in order to protect our skin. This is why our skin becomes darker after spending time in the sun.
Flavoxanthin is a carotenoid pigment that is found in plants. It is responsible for the yellow, orange, and red colors of fruits and vegetables. Carotene is another carotenoid pigment that is found in plants. It is responsible for the orange color of carrots and pumpkins. Xanthophyll is a carotenoid pigment that is found in plants. It is responsible for the yellow, orange, and red colors of fruits and vegetables.
These pigments are not responsible for the darkening of our skin after exposure to the sun.