Concept:Liners are ships that travel on fixed routes and follow regular timetables across seas and oceans.Explanation:Passenger liners carry people on specific high-sea routes at fixed times.Cargo liners carry goods on similar fixed ocean routes and schedules.Tramp liners have no fixed route or schedule and are hired as needed.Coastal liners operate along coastlines, not on the high seas.So, vessels operating on specific routes on high seas and oceans are passenger liners and cargo liners.Answer:D. Passenger Liners and Cargo Liners