What? It's a normal distribution graph. The height of the curve denotes how many of a particular group (group is denoted by the blue and green curves) score with regard to some trait x. The y-values for A and B on the graph are irrelevant.
You are right, of course. A dumb mistake of mine.
It's pretty clear from the totality of this person's comments that they are here to obfuscate and troll. Not sure why this is allowed on HN.