Variable Cells Constraints If the Right-Hand Side of Resource a Changes to 10

Variable cells
$$\begin{array} { | r | r | r | r | r | r | r | } \hline \text { Cell } & \text { Name } & \begin{array} { c } \text { Final } \\\text { Value }\end{array} & \begin{array} { c } \text { Reduced } \\\text { Cost }\end{array} & \begin{array} { c } \text { Objective } \\\text { Codficient }\end{array} & \begin{array} { c } \text { Allowable } \\\text { Increase }\end{array} & \begin{array} { c } \text { Allowuble } \\\text { Decrease }\end{array} \\\hline \text { \$B\$6 } & \text { Activity 1 } & 3 & 0 & 30 & 23 & 17 \\\hline \text { \$C\$6 } & \text { Activity 2 } & 6 & 0 & 40 & 50 & 10 \\\hline \text { \$D\$6 } & \text { Activity 3 } & 0 & - 7 & 20 & 7 & 1 \mathrm { E } + 30 \\\hline\end{array}$$
Constraints
$\begin{array}{|r|r|r|r|r|r|r|}\hline \text { Cell } & \text { Name } & \begin{array}{c}\text { Final } \\\text { Value }\end{array} & \begin{array}{c}\text { Shadow } \\\text { Price }\end{array} & \begin{array}{c}\text { Constraint } \\\text { R.H. Side }\end{array} & {\begin{array}{c}\text { Allowable } \\\text { Increase }\end{array}} & \begin{array}{c}\text { Allowable } \\\text { Decrease }\end{array} \\\hline \$ \mathrm{E} \$ 2 & \text { Resource A } & 20 & 7.78 & 20 & 10 & 12.5 \\\hline \$ \mathrm{E} \$ 3 & \text { Resource B } & 30 & 6 & 30 & 50 & 10 \\\hline \$ \mathrm{E} \$ 4 & \text { Resource C } & 18 & \mathrm{0} & 40 & 1 \mathrm{E}+30 & 22\\\hline\end{array}$
If the right-hand side of Resource A changes to 10, then the objective function value:

A) will decrease by $12.50.
B) will decrease by $125.
C) will decrease by $77.80.
D) will remain the same.
E) can only be discovered by resolving the problem.