If the Long-Run Market Supply Curve Is Perfectly Elastic, a Decrease

If the long-run market supply curve is perfectly elastic, a decrease in variable cost will:

A) shift the supply curve upward to a higher market-clearing price level.
B) shift the supply curve downward to a lower market-clearing price level.
C) shift the supply curve to the right to a higher market-clearing output.
D) shift the supply curve to the left to a lower market-clearing output.