You are evaluating a 58 year old man with chest pain. The BP is 92/50 and HR is 92/mi, nonlabored respiratory rate is 14 breaths/min and the pulse ox reading is 97. What is the most likely diagnosis? 1) Myocardial infarction 2) Pulmonary embolism 3) Pneumonia 4) Gastroesophageal reflux disease