A 75-year-old man presents to the emergency department with persistent right shoulder pain for the past month. He also reports increased fatigue and a 30-pound weight loss over the past several months. He has been smoking cigarettes for the past 40 years. On exam, the range of motion of his right shoulder is normal, and no swelling is noted. He has right-sided ptosis and a pinpoint right pupil, but his facial muscles are otherwise intact. When testing handgrip strength, his right hand is weaker than the left. Which of the following diagnostic tests would most likely reveal the underlying diagnosis?A. Chest x-rayB. Thyroid-stimulating hormoneC. Brain magnetic resonance imaging (MRI)D. Lyme enzyme-linked immunosorbent assay