Q. A 52-year-old man presents to the emergency department with a 2-hour history of intense chest pain that started while he was mowing the lawn. He describes the pain as pressure-like, radiating to his left arm. His past medical history is significant for hypertension and smoking. His vital signs are stable. An ECG shows ST-segment depression in leads II, III, and aVF. The patient is admitted for unstable angina and he is started on the appropriate medications. The attending physician asks the medical student on rounds, "Which type of lipoprotein is primarily responsible for the development of this patient's condition?" Which of the following is the most likely answer?