Which epithelial membranes protect by forming a lining for all passages that are open to the exterior of the body?

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. Connective tissue: Connective tissue has an extensive and varied extracellular matrix, which includes collagen, elastin, and ground substance. This allows it to provide support, cushioning, and structure to the body.

B. Simple squamous epithelial: Simple squamous epithelium is a single layer of flat cells with minimal extracellular matrix, mainly involved in diffusion and filtration.

C. Stratified squamous epithelial: Stratified squamous epithelium consists of multiple layers of cells but has very little extracellular matrix, as it primarily functions in protection.

D. Cuboidal epithelial: Cuboidal epithelial tissue, like other epithelial types, has tightly packed cells with minimal extracellular matrix, mainly functioning in secretion and absorption.