Which one of the following statements provides the most credible explanation for the fact that human beings seem to surpass all other animal species in their thinking and learning capacities? a. only human beings have the capability to make tools. b. humans communicate regularly with one another and, in doing so, pass along what they’ve learned to future generations. c. human beings have a huge repertoire of instinctual behaviors from which they can draw when they encounter new experiences. d. human brains are smaller than those of other intelligent species (e. g., elephants, dolphins) and therefore can transmit messages more quickly and efficiently.