Consider the Following Variables, Defined as Follows: D = Debt-To-GDP

Consider the following variables, defined as follows: d = debt-to-GDP ratio
X = primary budget deficit as a percentage of GDP r = real interest rate on government bonds
G = growth rate of real GDP
Which of the following expressions correctly describes the change in the debt-to-GDP ratio?

A) Δd = x + r - g) + d
B) Δd = x + r - g) × d
C) Δd = xr - g) + d
D) Δd = xg - r) - d
E) Δd = x + g - r) × d