$1\mathrm{.}1$ Na$$ve Method

$\backslash$table$[[$Period$,\backslash$table$[[$Sales $($$$],[$Millions$)]],$Forecast,Error,$\backslash$table$[[$Absolute$],[$Error$]],\backslash$table$[[$Percentage$],[$Error$]],\backslash$table$[[$Squared$],[$Error$]]],[1,11,,,,,],[2,9,,,,,],[3,8,,,,,],[4,11,,,,,],[5,10,,,,,],[6,,,,,,],[,,,$BIAS,MAD,MAPE,MSE$]]$

Using the naive method, what is the forecast for time period $6?$

$11$

$10$

$9$

$10\mathrm{.}5$