In a linear programming model, the shadow price for a labor constraint is $$10,$ and the sensitivity range for the labor hours is $40$ to $60$ hours. If the current labor hours are $50,$ what is the increase in the objective value if $5$ additional hours of labor are added?

A$.$ $$10$

B$.$ $$50$

C$.$ $$100$

D$.$ The objective value remains unchanged