<Tr> <Td> presby - </Td> <Td> old age </Td> <Td> Greek </Td> <Td> presbyopia, presbycusis </Td> </Tr> <Tr> <Td> prim - </Td> <Td> Denotes something as' first' or' most - important' </Td> <Td> Latin prīmus, first, most important </Td> <Td> primary </Td> </Tr> <Tr> <Td> pro - </Td> <Td> Denotes something as' before' another (in (physical) position or time) </Td> <Td> Ancient Greek προ (pro), before, in front of </Td> <Td> procephalic </Td> </Tr> <Tr> <Td> proct - </Td> <Td> anus, rectum </Td> <Td> </Td> <Td> proctology </Td> </Tr>

Which of these word parts is a root that means pertaining to the brain