Answer: They should not
Step-by-step explanation:
The Social cost of a project refers to the total cost that society incurs as a result of the project. This includes the actual costs to the investors as well as the cost to society such as pollution. Likewise the social benefit is the entire benefit that accrues from the project.
When using the Social Cost Benefit Analysis, one should not pick a project that has a higher social cost than social benefit because it would lead to a social loss. In order words, the project would cost society more than society would benefit from it so there is no need to embark on such a project.