Which of the following mortis types refers to the postmortem stiffening of the body muscles?

Rigor mortis refers specifically to the stiffening of the muscles after death. This physiological process occurs as a result of biochemical changes in the muscles when the body ceases to function. After death, ATP (adenosine triphosphate) production halts, leading to a depletion of this energy molecule, which is necessary for muscle relaxation. As a result, the muscles stiffen, making the body rigid. Rigor mortis typically begins to set in a few hours after death and can last for several days before the body begins to relax again as decomposition processes take place.

This process is significant in forensic science as it can help establish the time of death. Other types of mortis, such as livor mortis (the settling of blood due to gravity) and algor mortis (the cooling of the body), refer to different postmortem changes and do not involve muscle stiffness.