Which of the following statements about autoimmune diseases is true?

• A. The body attacks foreign pathogens only.
• B. The body attacks its own healthy cells.
• C. The body has a genetic predisposition to viruses.
• D. The body produces an excess of insulin.

Answer: (B)

Autoimmune diseases happen when the immune system turns against the body’s own tissues. That makes the statement that the body attacks its own healthy cells true. The immune system’s job is to defend against foreign invaders, so symptoms arise when it mistakenly targets the body's own cells, leading to inflammation and tissue damage depending on which part is affected. Some autoimmune conditions can be influenced by genetics, but the idea that the body is predisposed to viruses isn’t the defining feature. Producing an excess of insulin isn’t a typical hallmark either; in many autoimmune conditions affecting the pancreas, insulin production actually decreases due to destruction of the insulin-producing cells.