Final answer:
A client is excluded from hospice care if they are participating in a clinical trial, as this indicates ongoing curative treatment which is contrary to hospice philosophy.
Step-by-step explanation:
The criterion that excludes a client from hospice care is if the client entered a clinical trial through the National Cancer Institute. Hospice care is for individuals who have stopped curative treatments and are instead focusing on the quality of life at the end of life. Participation in a clinical trial indicates that the patient is still seeking active therapy, which is not in alignment with the hospice philosophy of care that emphasizes comfort and palliative care over aggressive treatment.