Sam travelled $$\rm 2400 m$$ from his home to the school.  Which of the following is equal to this distance? 
选项为:A:$$\rm 2km$$ $$4 m$$  B:$$\rm 2km$$ $$40 m$$  C:$$\rm 2km$$ $$400 m$$  D:$$\rm 20km$$ $$40 m$$  请回答其中一个选项.