Which of the following is NOT one of the reasons why it is difficult to determine whether a business practice is sustainable or unsustainable?

aUnsustainable levels of production could be positive in the short term and negative in the long term.

bBusiness owners have a clear incentive to only use practices that take into consideration long term consequences.

cWe cannot objectively say whether a policy is negative or positive.

dThe costs and benefits of policy accrue differently to different stakeholders.