Which type of autoimmune disease primarily affects the thyroid gland?

Graves' disease is a specific type of autoimmune disorder that primarily targets the thyroid gland, leading to its overactivity, or hyperthyroidism. In this condition, the immune system mistakenly produces antibodies that stimulate the thyroid, causing it to produce excessive amounts of thyroid hormones. These hormones are crucial for regulating metabolism, and their overproduction can result in a variety of symptoms such as weight loss, increased heart rate, and anxiety.

The other options listed affect different systems or glands within the body. Systemic lupus erythematosus is a systemic autoimmune disease that can affect multiple organs, including the skin and kidneys, but it is not confined to the thyroid. Addison's disease is an adrenal insufficiency condition resulting from damage to the adrenal glands and does not primarily involve the thyroid. Multiple sclerosis is a neurological disorder that affects the central nervous system by attacking the myelin sheath surrounding nerve fibers, again unrelated to thyroid function. Therefore, Graves' disease is the correct choice as it is the only condition among the options listed that is specifically characterized by thyroid dysfunction due to an autoimmune process.