Why do some primates have larger brains than others? The reason is usually considered to be social behavior, that is, primates live in larger and more complex social groups. In order to better deal with various social relationships, they need a bigger brain. Which of the following, if true, cannot be questioned? ['It is easier to predict brain size through dietary characteristics of primates than community complexity.', 'Some primates, such as orangutans, usually live alone, but their brains are also large.', 'The size of the cerebral cortex is not directly related to the size of the brain, but it is very important for primate cognition, spatial reasoning, etc.', 'In primates, the fruit-eating brain is larger than the leaf-eating, because the fruit is more dispersed in time and space, and finding the fruit is a more complicated task.']