In January, 2,500 Quarts of Ice Cream Are Sold in Boston

In January, 2,500 quarts of ice cream are sold in Boston at $2 a quart.In February, 3,000 quarts are sold at $2.50 a quart.This change in quantity sold and price may have been caused by

A) a reduction in wages in the Boston area.
B) the introduction of labor-saving automated ice cream-packing machinery.
C) the release of a medical study showing that ice cream consumption improves mental health.
D) the decision by Boston ice cream sellers to eliminate discount coupons.