Which of the Following Is True

Which of the following is true?

A) Because businesses adjust their prices immediately, the short-run aggregate supply curve is vertical.
B) Producers adjust their prices only in the long run, so the short-run aggregate supply curve is upward-sloping.
C) Because businesses adjust prices at different speeds, there is partial but incomplete adjustment of prices, and this results in the upward-sloping short-run aggregate supply curve.
D) In the very short run, the aggregate supply curve is upward-sloping, and this limits how much output can increase in the economy.