I think this is a poor-quality question and I agree with explanation. Even though I understand the explanation, I personally find misleading the verb "double" in the last option. What does it mean in this context?
I think that for a non-native speaker could be difficult to understand.

E. An article written by a pediatrician states that at-large baby carriers do not safely double as car seats.

Why it has been assumed that the pediatrician is talking about Dear One Baby Carrier ? He is just saying at large. Hence, I rejected this answer in mock. I too think D is best answer.

I think this is a poor-quality question and I don't agree with the explanation.

I think this is question has low-quality choices. The argument is that this is the "safest" carrier available, implying that there is a comparison with other carriers and that this is the safest option. Option E highlights a risk for ALL carriers, which would actually be irrelevant to the conclusion. Option D is correct imo since it specifically highlights a risk only for Dear One Baby Carrier.

Hi, I think A is a much better choice than E. For these reasons:

Perhaps best of all, the Dear One Baby Carrier converts easily from an at-large carrier to a car seat, reducing the risk to the baby posed by being shifted from one carrier to another.
This is the claim made by the manufacturer, the key safety features are making it less risky for the baby while it is being shifted into the car or after being shifted into the car seat, etc.

The interior design has been comfort-tested by thousands of infants, and the exterior handles have been designed with the arms and hands of caring parents in mind.
There is room for the argument that the baby carriers are not designed properly, because of the number of accidents that occur while the primary caretaker who was kept in mind while designing, was shifting the baby into the car, implying that perhaps the carrier was not designed well.



Oprion E
why not option E because 1. I doubt the validity of the pediatrician's conclusion, I don't have enough information to believe in his/her opinion;
moreover, the manufacturer already stated that the Dear One Baby Carrier converts easily from an at-large carrier to a car seat, reducing the risk to the baby posed by being shifted from one carrier to another. If a paediatrician thinks that at-large baby carriers do not double/fold/become half/change their shape safely , even then it does not convince that the Dear One Baby Carrier is not safe at-large.