The correct option is C Myasthenia gravis
The disorder due to which the immune system of the body attacks self cells is called an autoimmune disorder. Myasthenia gravis is an autoimmune disorder which affects the neuromuscular junction leading to fatigue and weakening of skeletal muscles.
Gout is a disease caused due to accumulation of uric acid in the joints leading to inflamed joints..
Osteoporosis is a condition caused due to loss of bone mass which makes it brittle. This is commonly seen in post menopausal women.
Muscular dystrophy is a genetic disorder which causes progressive degeneration of skeletal muscles.