To get to wok on time, they have to leave at 6.00 a.m. 

A. They always leave for work at 6.00 a.m. 

B. Getting to work on time, for them, means leaving at 6.00 am. 

C. They have to leave very early to catch a bus to work. 

D. Leaving at 6.00 am, they have never been late for work.