Help Needed to short list the right answer

[suyash.tiwari]

Some animals, such as dolphins, dogs, and African grey parrots, seem to exhibit cognitive functions typically
associated with higher-order primates such as chimpanzees, gorillas, and humans. Some parrots, for example,
have vocabularies of hundreds of words that they can string together in a comprehensible syntax. This clearly
shows that humans and primates are not the only animals capable of using language to communicate. One parrot,
named Alex, has been known to ask to be petted or kissed and will exhibit aggression if the gesture offered is not
the specific one requested. Which of the following, if true, would most strengthen the conclusion above?
- Dolphins can be trained to assist divers in ocean rescues.
- Gorillas in captivity often learn hand signals for food and water.
- Dogs are capable of sensing their owners’ moods and often exhibit concern if they sense sadness.
- Chimpanzees can memorize long sequences of key punches on machines that dispense food.
- Alex does not exhibit aggression when offered a gesture that he specifically requested.
OA:E
OE:(E) CORRECT. If Alex does not exhibit aggression when offered a gesture that
he specifically requested, it suggests that Alex can tell the difference between the
gestures that he requests and those that he does not. In other words, he is a
non-primate / non-human but he is communicating via language. If he also
exhibited aggression when offered the gestures he requested, it would be more
difficult to claim that he was communicating via language.

What about D ?
Even the dog comes in the category of those discussed and he is able to communicate effeciently when he is expressing concern in the same way the parrot expresses aggresiveness.

I find D better.

Please help me here.

[tim]

As per the forum rules, we need a verifiable source for the problem before we can deal with this question. If the question is not one of ours or one that is copyright-free, we will have to delete the question..

[suyash.tiwari]

As per the forum rules, we need a verifiable source for the problem before we can deal with this question. If the question is not one of ours or one that is copyright-free, we will have to delete the question..

I got this question from a private tutor's lecture notes.
Not sure about the author.

[tim]

then we won't be able to help with this one..