The nurse is teaching a health promotion class for adults about the effects of sun exposure on skin. Which statement about the function of collagen is correct?

A. Cell division occurs with the replication of parent cell's DNA distributed to daughter cells with duplicated chromosomes. This describes normal cell division (mitosis), not cancerous growth. In healthy cells, division is controlled, and errors are corrected by regulatory mechanisms.
B. Cells proliferate until a finite cell density is reached, which is determined by the availability of growth factors. Normal cells exhibit contact inhibition, meaning they stop dividing when they reach a certain density. Cancer cells ignore these regulatory signals and continue to grow uncontrollably.
C. Abnormal cell growth that remains confined to its original location, without invading surrounding tissue or spreading. This describes benign tumors, which do not spread. Cancerous (malignant) tumors, however, invade nearby tissues and can metastasize to distant organs.
D. Alteration of cellular genetics proliferates a mutated cell that progresses to surrounding and distant tissues. Cancer begins with genetic mutations that cause uncontrolled cell proliferation. As cancer progresses, cells invade surrounding tissues and may spread (metastasize) to distant sites via the blood and lymphatic systems. This is the defining characteristic of malignancy.

A. It is the main structural component of the dermis which provides strength and elasticity. Collagen is the primary protein in the dermis, responsible for maintaining skin strength, firmness, and elasticity. Sun exposure damages collagen fibers, leading to wrinkles, sagging skin, and premature aging.
B. It increases skin elasticity with the aging process. Collagen production decreases with age, leading to reduced skin elasticity and increased wrinkle formation. Sun damage accelerates this process by breaking down collagen fibers.
C. It forms the ridges and valleys which provide traction for grasping objects and surfaces. Friction ridges (fingerprints) are formed by the dermal papillae, not collagen. They provide grip and are genetically determined.
D. It is an extensive network of blood vessels that regulates body temperature. The dermis contains a network of blood vessels for temperature regulation, but this function is not related to collagen. Instead, collagen provides structural support to the skin.