Final answer:
Dermal thickening is caused by the increased production of connective tissue, particularly collagen fibers, which occurs during processes such as scar formation after wound healing.
Step-by-step explanation:
The cause of dermal thickening is B. increased production of connective tissue. The dermis is the inner and thicker layer of skin that consists primarily of connective tissue. The basic anatomy of the dermis includes a matrix of connective tissues, which involve collagen fibers for toughness and elastin fibers for elasticity. Dermal thickening typically occurs as a result of increased collagen fiber production, which could happen during wound healing as scar tissue forms. Collagen-rich scar tissue is different from normal skin and contributes to the thickening of the dermis in the affected area.