A 66-year-old postmenopausal woman presents with severe iron-deficiency anemia (Hb 8.4 g/dL, MCV 72 fL, ferritin 8 ng/mL). Upper GI endoscopy is normal, and FIT is strongly positive. Colonoscopy reveals the lesion marked **A** in the diagram—a 35 mm sessile polyp on the medial wall of the cecum with a lobulated, velvety surface, central shallow ulcer with fresh red blood, and contact bleeding on gentle manipulation. Narrow-band imaging shows regular mesh-like vessels (JNET 2A), and chromoendoscopy confirms a laterally spreading tumor (LST-G-M). Biopsies show tubulovillous adenoma with high-grade dysplasia but no unequivocal invasion. Given the size, location, and histology of the structure marked **A**, which of the following is the MOST appropriate initial management?