The correct answer to the question is option 4, Melanin. A pigment is a substance that gives color to tissues or objects. Melanin is a pigment that is responsible for the color of our hair, skin, and eyes. It is produced by specialized cells called melanocytes. Melanin absorbs and scatters ultraviolet (UV) radiation from the sun, providing protection to the underlying tissues from the harmful effects of UV rays.

Option 1, Albumin, is a protein found in blood plasma and is responsible for maintaining the osmotic pressure of the blood. However, it is not a pigment.

Option 2, Elastin, is a protein that is responsible for the elasticity of connective tissues. It helps maintain the shape and flexibility of organs, but it is not a pigment.

Option 3, Keratin, is a protein found in structures such as hair, nails, and the outermost layer of the skin. It provides strength and protection to these structures but is not a pigment.

In conclusion, melanin is the only option among the given choices that is a pigment.