Ante-mortem hanging means the person was alive when the hanging occurred. We need to find a sign that indicates a vital reaction (a reaction of a living body).
Step 1: Analyze the options.
(1) Dripping of Saliva: Saliva production is a physiological process that occurs in a living person. In hanging, pressure on the salivary glands and stimulation of certain nerves can cause excess salivation, which then drips down the chin and chest. This is a strong indicator of ante-mortem hanging.
(2) Fracture of femur bone: This is not typically associated with hanging and is not a vital reaction.
(3) Post-mortem caloricity: This refers to a rise in body temperature after death, a post-mortem phenomenon, not an ante-mortem sign.
(4) Presence of vomit: While this can happen before death, it is not a specific or reliable indicator of ante-mortem hanging, as it can occur for many reasons.
Step 2: Conclude. The most reliable sign among the choices that confirms the hanging occurred while the individual was alive is the dripping of saliva due to vital physiological reactions.