Final answer:
The Constitutio Antoniana granted Roman citizenship to all free inhabitants of the Roman Empire, enabling them to appeal to Roman law and inherit property.
Step-by-step explanation:
The Constitutio Antoniana, enacted in 212 CE by Emperor Caracalla, is the law referred to in option C) the law rendering all the free inhabitants of the empire Roman citizenship. This legal decree was significant as it extended Roman citizenship to nearly all free men and women in the empire, thus enabling more people to appeal to Roman law, inherit property, and be exempt from certain harsher punishments. The extension of citizenship also had practical reasons, such as making it easier to collect taxes from a larger base of citizens.