Final answer:
Marietta is in the 'bargaining' stage of Elisabeth Kübler-Ross's model of death and dying, which is an attempt to negotiate with a higher power for more time or relief.
Step-by-step explanation:
Marietta, who is terminally ill and promises to go to church every Sunday if God will let her live to see the birth of her first grandchild, reflects the bargaining stage of death and dying according to Elisabeth Kübler-Ross's five-stage model. Kübler-Ross defined this third stage as an attempt by individuals who acknowledge their illness to negotiate with a higher power for more time or relief from their condition. This stage comes after denial and anger but before depression and acceptance in the process of coping with the proximity of death.