he mean square error $($MSE$)$ for the forecasts shown in the following table is:

Month

Forecast Demand

Actual Demand

April

$170$

$180$

May

$225$

$200$

June

$210$

$200$

July

$260$

$240$

August

$200$

$230$

a$.$ more than $250$ but less than or equal to $300.$

b$.$ more than $300$ but less than or equal to $350.$

c$.$ more than $350$ but less than or equal to $400.$

d$.$ more than $400$ but less than or equal to $450.$