The average monthly rent for one-bedroom apartments in Chattanooga has been $700. Because of the downturn in the real estate market, it is believed that there has been a decrease in the average rental. The correct hypotheses to be tested are:
a. H0:  m = 700            Ha:  m < 700
b. H0:  m = 700            Ha:   m ¹ 700
c. H0:  m > 700            Ha:  m £700
d. H0:  m < 700            Ha:  m ³ 700