What number should replace the question mark？

单项选择题I'd love to help you look for all those things but I'm a bit pushed for time today．Why don't we split up and meet back in a couple of hours for a quick cuppa and then I can have a look at what you've bought．

单项选择题Our family was truly a matriarchy，because my grandmother had to raise her children and provide for them all by herself；my grandfather had died when his sons and daughter were quite young．

单项选择题A first-class business establishment will fully recompense its customers if there is ever any dissatisfaction with the service or product．

单项选择题In Greek mythology，the hero usually finds himself in a terrible predicament in which he has to face a fate which has been foretold by the Oracle at Delphi．

单项选择题In the western countries，a person who serves the guests in a restaurant expects a gratuity in appreciation for good service．