Which of the following type of lipids (fats) have shown to increase the risk of heart disease by forming plaques of fat on blood vessels?

A. Bilirubin: Bilirubin is a yellow pigment derived from the breakdown of red blood cells, associated with jaundice rather than freckles or moles.

B. Carotene: Carotene is an orange pigment found in foods like carrots and can contribute to skin tone but is not the main factor in moles or vitiligo.

C. Keratin: Keratin is a structural protein found in skin, hair, and nails but does not influence pigmentation.

D. Melanin: Melanin is the pigment responsible for skin color, moles, freckles, and conditions like vitiligo, which causes depigmentation.

A. Appear yellow: Yellow skin is often due to jaundice (bilirubin accumulation) or carotene deposits, not keratinization.

B. Are hardened and water-resistant: Keratinization involves the production of keratin, making the epidermis tough and water-resistant to protect against dehydration and external damage.

C. Appear cyanotic: Cyanosis is a bluish discoloration due to hypoxia, not keratinization.

D. Have been replaced by connective tissue: Keratinized epidermal cells are still part of the skin, whereas connective tissue replacement occurs in scarring or wound healing.