Assume there are three actions possible $\{$a$0,$ a$1,$ a$2,$ a$3\}$ the true reward $($r$)$ for each action is as follows:

r$($a$0)=0\mathrm{.}2$

r$($a$1)=0\mathrm{.}57$

r$($a$2)=1\mathrm{.}5$

r$($a$3)=-0\mathrm{.}57$

What is a$*($best action$)$ is equal to$?$