问题: WhydoestheauthormentionthepopulationofCanada,AustraliaandEnglandandWales?
A: Totelluswhatsmallpopulationsthesecountrieshave.
B:ecausethepopulationofthesethreecountriesareincreasingasfastastheworldpopulation.
C:ecausethepopulationofthesethreecountriesarenotincreasingasfastastheworldpopulation.
D:Togiveussomeideaabouthowfasttheworldpopulationisincreasing.