What is multifactor productivity $($labor $+$ material $+$ overhead$)$ of the current process?

a$.$ less than or equal to $8\mathrm{.}0$

b$.$ greater than $8\mathrm{.}0$ but less than or equal to $10\mathrm{.}0$

c$.$ greater than $10\mathrm{.}0$ but less than or equal to $12\mathrm{.}0$

d$.$ greater than $12\mathrm{.}0$