Answer:
d. all of these
Step-by-step explanation:
Over the past century, many researchers have questioned whether nonhuman primates could communicate with each other and whether they could communicate with each other. After much research and testing with different nonhuman primates, it was concluded that primates not only communicate, but this communication is done through various processes and has a similar pace to the rate of communication between humans, after all, if genetic differences between humans and chimpanzees are very small.
Among the processes of communication between non-human primates we can mention: vocalization, facial expressions and displays, which ensure that these animals talk to each other.