Fresh Market Doughnuts prepares and sells fresh doughnuts. The regular price is $$1\mathrm{.}50.$ Day$-$old doughnuts are sold for $$0\mathrm{.}25$ each. The cost of baking doughnuts is $$1\mathrm{.}00,$ and demand is estimated to be normally distributed with a mean of $50$ and a standard deviation of $8.$ Calculate the optimal service level.

Group of answer choices

$0\mathrm{.}50$

$0\mathrm{.}60$

$0\mathrm{.}40$

$0\mathrm{.}83$

None of the above.