While travelling on a road outside a built-up area, you were about to overtake a truck. After you turned on your left direction indicator, the driver of the truck turned on and then turned off the left direction indicator. What might this mean?

1. 1The driver of the truck, in violation of the Road Traffic Rules, is hindering the overtake.
2. 2The driver of the truck is warning you of a danger during the overtake that you are unable to detect.
3. 3The driver of the truck was about to make a overtake himself but, upon seeing your actions, abandoned his plan.