You are answering a USMLE-style medical question. Question: A 31-year-old G1-P0 woman at 28-weeks gestation presents with shortness of breath and nonspecific right-sided chest pain that is worse with inspiration. She works as a graduate student at the local university, and she informs you that she recently returned to the west coast from a trip to New York for an Economics conference. Her medical history is positive only for frequent bouts of sinusitis. She currently denies any smoking, drinks a glass of red wine/day, and she denies any past illicit drug use. The vital signs include: temperature 36.7°C (98.0°F), blood pressure 126/74 mm Hg, heart rate 87/min, and respiratory rate 23/min. Her physical examination shows decreased air movement throughout the right lung but otherwise clear lungs on auscultation, grade 2/6 holosystolic murmur, and a gravid uterus without acute findings. On physical examination, she is afebrile, tachycardic to 121/min, normotensive, and demonstrates an O2 saturation of 92%. Which of the following is the best next step in the evaluation of the most likely diagnosis for this patient? Options: A) ECG B) Chest radiography C) V/Q scan D) CT pulmonary angiogram Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.