Answer Choice

@rzamor87, Could you please clarify what do you mean by positive argument? This question asks us to find a logical structure most like that of the argument presented. The argument is structured as follows: Full-term babies (B) are born with reflexes that disappear by age of two months (R). Because this 3-month old exhibits such reflexes, this baby is not a normal full-term baby.Note that conclusion is a contrapositive of the premise , which makes it a logically valid argument. I am going to use "~" for not to diagram the argument, B for "baby" and "R" for reflexes. B -> ~R The premise essentially says that IF it is a full-term baby, THEN after 2 months there are NO reflexes. R -> ~B The conclusion says that IF there are reflexes in a 3-month old, THEN it is NOT a full term baby. The correct answer choice D follows the exact same reasoning. Because opossums (O) have abdominal pouches (P) and this animal lacks any such pouch, this animal is not an opossum. Let's diagram this argument. O ->P IF the animal is an opossum, THEN it has a pouch. ~P -> ~O IF the animal does NOT have a pouch, THEN it is NOT an opossum. Let me know if this is helpful and if you have any more questions.

Thank you for following up. I was able to get the correct answer but upon hearing the explanation I overheard a positive logical argument. I just wondered if there was an explanation for that.