Correct option:(3)Myasthenia gravis
Solution:

• Myasthenia gravis is a chronic auto immune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle.
• Gout is caused due to deposition of uric acid crystals in joints leading to its inflammation.
• Inflammation of joints is commonly known as arthritis.
• Muscular dystrophy is a genetic disorder which results in progressive degeneration of skeletal muscle.