The Figure Given Below Shows the Aggregate Demand and Supply

Multiple Choice

The figure given below shows the aggregate demand and supply curves of a perfectly competitive market.Figure 10.7

-When Glaxo-Wellcome introduced AZT, an AIDS drug, it was able to enjoy high profits because:

A) the drug was highly recommended by doctors.
B) of the quick response of rivals in introducing substitute drugs.
C) of barriers to entry provided by patents.
D) of its competitive price in the pharmaceutical industry.
E) it experienced constant returns to scale in the long run.