Love and attachment both were there, but best word to describe their relationship according to me would be C. Attachment. Buck killed the Indians because they killed John, that' revenge according to us. There's revenge in friendship in love but I am saying C. because, in love and friendship theoretically you won't necessarily kill someone, but when you are attached to something, you definitely could. To an animal love and friendship or trust doesn't mean anything. To them it's only attachment. Many suggest that it is A. Love, but it is my personal opinion. You could go with either one.
