Diagramming

Hello @KatrinaMusa, Your diagram is valid, I do not see any problems with it. The conclusion of this argument is the contrapositive of the premise, and your diagram matches that. You want to look for the answer choice that has the same format. Did you have trouble doing so? If not, you approached this question correctly.

I inferred using All in the first sentence and wrote the general principle backwards which made me select A as the correct answer. Why don't we use ALL to introduce the SC in this example?

Hi @zacharylouiskane@gmail.com We do use "all" to introduce the sufficient condition; however, its placement in the sentence has tripped a few students up. The stimulus is not saying "all instinctive reflexes will disappear by the age of two months in normal full-term babies." The word "all" is used to refer to "newborn babies" i.e. "all newborn babies are born with certain instinctive reflexes that disappear by the age of two months." Make sure you read through sentences carefully to ensure that you select the proper sufficient and necessary conditions. Sometimes, indicator words will be confusingly placed as in this stimulus and will require a bit of extra thought to determine which condition is which. Hope this is helpful! Please let us know if you have any further questions.