Final answer:
According to the defender of the Best Bet Argument, abolishing the death penalty can make killing more attractive to those already inclined to commit murder and can lead to an increase in overall murder rates.
Step-by-step explanation:
The defender of the Best Bet Argument suggests that when we abolish the death penalty, we risk making killing more attractive to those who are already disposed to commit murder. They argue that abolishing the death penalty gives everyone else an incentive to stay out of the way, which can result in an increase in overall murder rates.