$\backslash$table$[[$Year$,$Potential Real GDP$,$Real GDP$,$Price Level$],[2018,$$$18\mathrm{.}0$ trillion,$$18\mathrm{.}0$ trillion,$150],[2019,18\mathrm{.}5$ trillion,$18\mathrm{.}8$ trillion,$154]]$

Consider the hypothetical information in the teble for potential real GDP$,$ real GDP$,$ and the price level in $2018$ and in $2019$ if Congress and the president do not use fiscal policy. If Congress and the president want to keep real GDP at its potential level in $2019,$ they should

A$.$ conduct expansionary fiscal policy.

B$.$ buy Treasury securities$.$

C$.$ decrease the discount rate.

D$.$ decrease govemment purchases.