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.

i am completely lost on this one....i mean i dont understand where is this communication happening....Choice E says that alex express no aggression but again how does it show that alex is communicating and with whom???/.....I am completely bowled....Please explain....

Regards,
Phil

Alex is communicating with humans of course, probably its master.

Option E is correct because among other things it's the only option that talks about communication.

Options B & D can be left out since chimps and gorillas come under the primate categories according to the argument.

Among the other three options, in C dogs are sensing or perceiving which is not the same thing as communicating.

In A dolphins are being trained but training is a one-way process whereas communication is a two-way process.

In option E suppose Alex asks you to pet him and no matter whether you pet him or not he gets aggressive, then it is not communication. But the option E, together with the evidence in the argument implies that he only gets aggressive when he doesn't get the desired response. This means that he can communicate and also comprehend the response - a two-way process.

Ideally you shouldn't have to think this far - the fact that none of the other options involve communication except E should get you to the answer.

Cheers!

Very Good Explanation to very good question

E provides evidence of an ability on the part of the bird to recognize the connection between the words it uses and the behavior it elicits, something that if true certainly provides support for the bird's ability to communicate effectively..

_________________
Tim Sanders
Manhattan GMAT Instructor