Final answer:
According to Kant, 'rational beings only' are considered as persons due to their rational nature, which gives them inherent worth and dignity.
Step-by-step explanation:
According to Kant, rational beings are considered as persons due to their rational nature. So the correct answer is C) Rational beings only. Kant believed that personhood is based on the ability to act rationally, which is a characteristic that imbues individuals with inherent worth and dignity. Kant's philosophy posits that it is this capacity for rationality that sets persons apart as 'ends in themselves'. This perspective implies that not all humans may necessarily qualify as 'persons' in his philosophical framework if they lack rationality, such as in cases of severe cognitive impairment. Conversely, if non-human entities were to possess rational capacities, Kant's framework would theoretically acknowledge them as persons as well.