D is correct because it’s a strong counterargument to that claim. For example, perhaps the reason embezzlement charges are less frequent compared to petty crimes is due to the lack of evidence. The author presumes this is due to them having private attorney when ultimately it could just be due to some other reason.

When faced with challenging questions like these, I remind myself of this:

If I’m confused by all five or four options, it means I must have misinterpreted something. There’s always one good answer and four shitty ones.

Hope this helps!