A Constant Inflation in the AD/AS Macro Model Is Only

A constant inflation in the AD/AS macro model is only possible when

A) AS shifts upward at a uniform rate and AD shifts downwards at a uniform rate.
B) AS shifts downward at a uniform rate and AD shifts upwards at a uniform rate.
C) AD shifts upwards at a uniform rate and AS shifts upwards at the same uniform rate.
D) AD shifts upwards at a uniform rate and AS shifts upwards at a higher uniform rate.
E) None of the above - constant inflation is not possible.