If the sample regression equation is hat$(y)=15-5x,$ which of the following is the correct interpretation of the estimated slope coefficient?

A$)$ For every unit increase in hat$(y),x$ increases, on average, by $5$ units.

B$)$ For every unit increase in $x,$hat$(y)$ decreases, on average, by $5$ units.

C$)$ For every unit increase in $x,$hat$(y)$ increases, on average, by $5$ units.

D$)$ For every unit increase in hat$(y),x$ decreases, on average, by $5$ units.