Final answer:
Option C, which states that it cost three times as much to put prisoners to death than it does to give them life in prison, is the reason that best supports the central claim that the death penalty should be abolished because it is too expensive.
Step-by-step explanation:
The central claim in the example given is that 'the death penalty should be abolished because it is too expensive.' The reason that best supports this central claim is option C: 'It cost three times as much to put prisoners to death than it does to give them life in prison.' This reason provides evidence that the death penalty is financially burdensome and supports the argument that it should be abolished.