Pedunculated Colon Polyp — Snare Polypectomy

A 58-year-old woman undergoes screening colonoscopy and a 25 mm pedunculated polyp with a thick 8 mm stalk is identified in the sigmoid colon. An endoloop is placed at the stalk base for prophylactic hemostasis. The structure marked **C** (snare positioned at the mid-stalk) is then used to transect the polyp. Why is positioning the snare at the mid-stalk level, rather than at the stalk base or polyp head, the procedurally critical step in this scenario?