A deck building project is estimated to cost $$50,000$ with a timeline of $20$ days. After $10$ days, the project manager finds that $80\%$ of the project is complete and Actual costs are $$50,000.$ What is the Cost Performance Index $($CPI$)?$

$($A$)0\mathrm{.}5$

$($B$)1$

$0\mathrm{.}8$

$($D$)1\mathrm{.}6$