Using the data set below, what would be the forecast for period $4$ using a three period moving average: $($Choose the closest answer.$)$

$\backslash$table$[[$Period$,$Actual Demand$],[1,10,000],[2,12,400],[3,13,250],[4,15,750],[5,20,500],[6,18,500]]$

a$.12,244$

b$.11,500$

c$.14,008$

d$.11,883$