I have a good understanding of Displacement-time graphs and position-time graphs and how to interpret them. I take the IB diploma and came across this question from a 2009 paper with a displacement-position graph but our textbook does not help interpret it and neither can I find an internet article with explanations

Here is the question. So the answer is C meaning the velocity is downwards. But I thought the particle starts at its mean position, travels to the left and back to the mean position, and then begins travelling to the right. So at point P the particle should be moving in the right direction. The question says at the wave travels left to right so how can the velocity really be downwards?