A: To give yourself acceleration space if you decide to overtake
B: To get the best view of the road ahead
C: To leave a gap in case the vehicle stops and rolls back
D: To offer other drivers a safe gap if they want to overtake you
View hint
When following a large vehicle, keep well back. If you’re too close, you won’t be able to see the road ahead and the driver of the long vehicle might not be able to see you in their mirrors.