A 68-year old man has a 1-month history of hemoptysis and weakness. He has smoked 2 packs of cigarettes per day for 50 years. Eyelid ptosis is present bilaterally. Muscle testing shows increasing strength during several seconds of effort. An X-ray of the chest shows a mass on the left upper lobe of the lungs . Antibodies are most likely to cross-react between the mass and which of the following? (A) Muscle mitochondria (B) Myofilaments (C) Na+ – K+ pump (D) Synaptic Ca2+ channels (E) Thyroid-stimulating hormone receptors