A cleaning company uses $10lbs$ each of chemicals $A,B$ and $C$ for each house it cleans. After some quality complaints, the company has decided to increase its use of chemical $A$ by an additional $10lbs$ for each house. By what $\%$ has productivity $($houses per pound of chemical$)$ fallen?

Select one:

a$.33\%$

b$.25\%$

c$.15\%$

d$.10\%$

e$.0\%$