| A. Being an evolutionarily advanced animal | B. Being morally upright | ||
| C. The possession of reason | D. The capacity for feeling pain | ||
(C) is the right answer. A rational being has to be treated by other rational beings as an end and not a means to an end.
You deserve better than to be treated as a means to an end even though you are a failure morally speaking (B).
Animals for Kant lack rationality and so are not citizens of the kingdom of ends (A)
The capacity to feel pain, the importance of which was insisted upon by Utilitarian Jeremy Bentham, did not admit you to the kingdom of ends either (D).