**Core Concept**
In judicial hanging, the "knot" is placed to ensure effective asphyxiation by restricting the airway. The anatomical location determines the mechanism of suffocation, primarily involving pressure on the pharynx and larynx, with the angle of jaw being a key landmark.

**Why the Correct Answer is Right**
The knot is placed **under the angle of jaw** to apply direct pressure on the pharynx and larynx, which are critical for airway patency. This position allows the force to be transmitted efficiently through the neck, compressing the airway and preventing airflow. The angle of jaw is anatomically ideal because it aligns with the natural curvature of the neck and provides optimal pressure without damaging the trachea or causing immediate cervical spine injury.

**Why Each Wrong Option is Incorrect**
Option A: Placing the knot on the **back of the neck** may not effectively compress the airway and could lead to improper positioning or less reliable asphyxiation.
Option C: Positioning the knot **below the chin** may not apply sufficient pressure on the pharynx and could result in poor effectiveness or an unsafe mechanism.
Option D: "Choice of hangman" is not a valid anatomical or forensic criterion; the knot placement is standardized based on medical principles, not personal preference.

**Clinical Pearl / High-Yield Fact**
In forensic medicine, the knot must be placed under the angle of jaw to ensure reliable and effective asphyxiation while minimizing risk of cervical fracture or accidental injury. This is a standard in judicial hanging procedures and is taught in forensic pathology curricula.

✓ Correct Answer: B. Under angle of jaw