Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

Which of the following best describes the aggregate supply curve in the short-run (e.g., 1 to 2 years)? The short run aggregate supply curve is:
Option A:flat because output is more flexible than prices in the short run.
Option B:vertical because wages and other input prices fully adjust to the price level.
Option C:upward sloping because input prices do not fully adjust to the price level in the short run.

Answer: C