Final answer:
Active dying is the period that typically covers the last 3-5 days before death, marking the final phase of a person's life and is part of the study of thanatology.
Step-by-step explanation:
Active dying is considered to be the last 3-5 days before death. This phase includes both biological and psychological changes as a person comes to terms with their mortality. Understanding this stage is part of thanatology, the study of death and dying, which is a significant aspect of end-of-life care and hospice programs. Hospice care often provides the necessary support during this time, allowing for a dignified and comfortable end-of-life experience.