Which among the following is an auto-immune disease?

Rheumatoid arthritis.

The correct answer is Option (3) → Rheumatoid arthritis.

Auto-immune diseases occur when the body's immune system mistakenly identifies its own healthy cells as foreign and attacks them. Normally, the immune system protects the body from harmful invaders like bacteria and viruses. However, in auto-immune diseases, this defense system malfunctions and begins to target self-cells, leading to inflammation, tissue damage, and dysfunction in various organs or systems. Rheumatoid arthritis which affects many people in our society is an auto-immune disease . In the case of rheumatoid arthritis, the immune system attacks the joints, causing inflammation, pain, swelling, and eventually joint damage.