Context:Cathy and Louise want a picture of their children and the children do what they are told because they know what is good for them . Erica and Johnny show up to take one last rip and all of a sudden it is over . The trip is complete , Ian and John drop off the crew at Britannia Yacht Harbour and go and pull the boat out .
Question What may have been reason behind the statement " they knew what is good for them ? "
Answer:
The kids were aware of the fact that they would be punished if they did n't what they were ordered to do .