Suppose That a More Efficient Way to Produce a Good

Suppose that a more efficient way to produce a good is discovered, thus lowering production costs for the good. This will cause:

A) ​an increase in supply, or a rightward shift of the supply curve.
B) ​a decrease in supply, or a leftward shift of the supply curve.
C) ​an increase in quantity supplied, or a movement down the supply curve.
D) ​a decrease in quantity supplied, or a movement up the supply curve.