Which score indicates the highest relative position? Round your answer to two decimal places, if necessary.

$($a$)$ A score of $3\mathrm{.}2$ on a test with $\stackrel{}{x}=4\mathrm{.}5$ and $s=1\mathrm{.}5.$

$($b$)$ A score of $610$ on a test with $\stackrel{}{x}=840$ and $s=200.$

$($c$)$ A score of $39$ on a test with $\stackrel{}{x}=53$ and $s=4.$

The score with the highest relative position is a $,$ since the z$-$score $=\_\_\_$ is highest.