Why, According to Carruthers, Does Our Attachment to Pets Not

Why, according to Carruthers, does our attachment to pets not give rise to a social-stability argument justifying an extension of moral standing to animals?

A) Pet-keeping and attachment to pets is not a universal feature of human nature.
B) Our attachment to pets is rarely as deep as attachments to relatives and children.
C) Granting moral standing to animals will open the floodgates to extending moral status to anything we care about.
D) Both a and b