Final answer:
Multiple sclerosis affects the myelin tissue of the nervous system, disrupting electrical impulses and causing neurological symptoms. Therefore correct option is D
Step-by-step explanation:
The anatomical structure affected in clients with the autoimmune disease multiple sclerosis (MS) is the myelin tissue of the nervous tissue. MS is an autoimmune disorder that targets and damages the myelin sheath - the protective covering that surrounds nerve fibers in the central nervous system. This damage disrupts the normal flow of electrical impulses along the nerves, leading to a range of neurological symptoms such as muscle weakness, balance and coordination difficulties, and cognitive impairments.