Which of the Following Correctly Describes One Reason Why the Aggregate

Which of the following correctly describes one reason why the aggregate demand (AD) curve slopes downward?

A) Aggregate expenditure increases as the price level rises,which leads to a rise in real GDP.
B) Decreases in the price level cause increases in privatE-sector wealth which lead to increases in desired consumption.
C) The increase in total output associated with the fall in the price level results in lower production costs.
D) When the price level falls,firms must be more competitive when output increases.
E) When the price level falls,consumers increase their saving rate.