The first sentence, a premise, tells us: “I don’t know much about animal tracks, but I do know that birds typically have four toes.â€
Our conclusion is that the track was made by some kind of bird.
Though it may be true that birds typically have four toes, with three pointing forward and one pointing back like the premises tell us, does that mean they are the only animals that can leave this kind of track? The argument doesn’t give us that information. What if, for instance, a raccoon or opossum has a similarly shaped foot and could leave a similar track? In order to conclude that the track was made by some kind of bird, you would need to know that some other kind of animal (like a raccoon or opossum) couldn’t have left it. Answer choice D, “does not establish that **only a bird** could have made the track†gets at this idea.
