This year the price of smart phones has fallen. Which of the following could be the cause of the decrease in the price of smart phones?
A. A decrease in consumer income that decreases the demand for smart phones
B. An improvement in technology of producing smart phones that increase the supply
C. An increase in the wages paid to workers who produce smart phones that decreases the supply of smart phones
D. Either A or C
E. Either A or B
Answer: E