Refer to the Diagram, in Which S1 and D1 Represent

Multiple Choice

Refer to the diagram, in which S1 and D1 represent the original supply and demand curves and S2 and D2 the new curves. In this market the indicated shift in supply may have been caused by

A) an increase in the wages paid to workers producing this good.
B) the development of more efficient machinery for producing this commodity.
C) this product becoming less fashionable.
D) an increase in consumer incomes.