Which of the following is an auto-immune disease?

Auto-immune disorders occur when our body's immune system assaults and destroys its own tissues without our knowledge. By accident, the body destroys its healthy tissues.

Myasthenia gravis is one of several auto-immune illnesses that affect the human body. It is a neuromuscular illness that causes muscle weakness and weariness.
Rheumatoid arthritis (RA) is a chronic auto-immune disease affecting the joints. Warm, swelling, and aching joints are common symptoms. Resting causes pain and stiffness to worsen.