<Li> Dual - clutch </Li> <Tr> <Td> <Ul> <Li> Continuously variable </Li> </Ul> </Td> </Tr> <Ul> <Li> Continuously variable </Li> </Ul> <Tr> <Th> Bicycle gearing </Th> </Tr>

Which one of the following is used to reverse the direction of rotation in a gearbox