On What Does the Steepness of the Short-Run Aggregate Supply

Multiple Choice

On what does the steepness of the short-run aggregate supply curve primarily depend?  

A)  on the length of time for which resource prices are fixed 
B)  on the length of time for which output prices are fixed 
C)  on the difference between the expected price level and the actual price level 
D)  on how quickly production costs increase as output expands