Final answer:
The theory that applies when a person convicted of murder is given the penalty of death is the death penalty itself, with certain restrictions and limitations in place.
Step-by-step explanation:
The theory that applies when a person convicted of murder is given the penalty of death is the death penalty itself. In some countries, including the United States, the death penalty is still a legal form of punishment for serious crimes such as murder. However, it's important to note that the application of the death penalty has been narrowed in recent years, with certain restrictions placed on who can be executed, such as individuals with intellectual disabilities or those who were under eighteen at the time of the offense.