Hello.
In an exam paper, I read:
"2 marks for an answer that mentions all the salient
answer, 1 mark for a ‘right lines’ solution), "
What is a 'right lines' solution?
It's a solution that shows that at least you are "on the right track"; your answer is "along the right lines". You are going in the right direction with your answer, but you haven't quite fully explained it.