Both b and d are most definitely not illegal -- deceptive yes, but not illegal.
If I sell you a crappy asset (imagine a company almost going bankrupt) for $10m and you don't do proper due diligence on said asset, then you have no right of complaining afterwards. No one is going to do your homework.
If I am your client, you have fiduciary responsibility to warn me - I am paying you commission to do due diligence.
If you know it is a crappy product, and don;t warn me, it is at the very least a SEC violation, punishable. Could also be viewed as fraud, and pursued as a crime.
