Answer: A, C and D.
Explanation:
With the options given above, options A, C and D are reasons why the ban on killing Bengal tigers hasn't been successful. When the punishment for killing Bengal tigers is not severe, people won't mind killing the tigers since they know they won't be severely punished for their action. Also, when the enforcement of the poaching law is weak and the potential profit from the illegal poaching is higher than the risk of getting caught, people will continue to kill the tigers.
For the law to be effective, there must be strict punishment for people who go against the law made.