A 58-year-old man from Delhi presents with acute onset chest pain radiating to the left arm for 2 hours. He is a known hypertensive on irregular treatment and a heavy smoker with a 30-pack-year history. Blood pressure is 165/95 mmHg, heart rate 102/min. ECG shows ST elevation in leads II, III, aVF. Troponin I is elevated at 2.8 ng/mL. Coronary angiography reveals a thrombotic occlusion of the right coronary artery with underlying atherosclerotic plaque. Which of the following pathological features of the atherosclerotic plaque most likely precipitated acute thrombosis in this patient?