With Extensive Training, Dolphins and Parrots Can Acquire a Vocabulary

With extensive training, dolphins and parrots can acquire a vocabulary and respond to short, novel sentences,

A) although they do so less consistently than a preschool child.
B) but only chimps can be taught to produce strings of three or more symbols that conform to a rule-based structure.
C) showing that they follow the same grammatical rules as humans in their own "language."
D) and are highly attuned to recognize human intentions that motivate use of language.