Final answer:
The denial stage of grief is a defense mechanism that helps individuals cope with the reality of loss or impending death, as described by Elisabeth Kübler-Ross in her book On Death and Dying.
Step-by-step explanation:
The denial stage of grief is a normal defense mechanism that buffers humans from unbearable reality. Elisabeth Kübler-Ross outlined the five stages of grief in her classic 1969 book On Death and Dying. The stages include denial, anger, bargaining, depression, and acceptance. The denial stage is characterized by initial shock and disbelief about the loss or the reality of impending death. Many people experience these stages in varying orders and intensity, with some not going through all five stages.