Seventeen-Year-Old Lisa Montague Practiced Piano for 3-4 Hours Each Day

Multiple Choice

Seventeen-year-old Lisa Montague practiced piano for 3-4 hours each day while preparing for music college auditions.Some of her pieces required sustained arm-muscle activity and she began to find them hard to play,even though she had previously played them easily.When she also started to have difficulty swallowing and chewing,she told her mother,who took her to the emergency room,where the physician noticed drooping eyelids and limitation of ocular motility.An electromyogram detected impaired nerve-to-muscle transmission.Administration of pyridostigmine rapidly improved Lisa's symptoms.Which of the following blood-test results would be most consistent with her condition?

A) elevated rheumatoid factor
B) elevated anti-myelin basic protein antibodies
C) elevated anti-acetylcholine receptor antibodies
D) elevated anti-nuclear antibodies
E) elevated anti-Rh antibodies.