Final answer:
In contractarianism, ethics are derived from the social contract, making none of the provided options the final authority.
Step-by-step explanation:
According to the moral theory of contractarianism, the final authority on ethics is d. none of the above. Contractarianism does not suggest that personal opinion, the law, or conventional wisdom are the final arbiters of ethical matters.
Instead, it is rooted in the concept of the social contract, wherein individuals must accept certain moral and political obligations to participate effectively in society, rather than simply adhere to subjective or legally mandated norms.