There are basically two factors that can cause the market supply to shift to the rightward: (i) A decrease in production costs shifts the market supply curve rightward. For example, a technological innovation which leads to a rise in labor productivity decreases the unit labor cost and causes the market supply curve to shift to the right. (ii) In the long run, an increase in the number of firms, i.e., new firms entering the industry, shifts the market supply curve rightward. The correct answer is E.