Macroeconomists Cannot Conduct Experiments in the Manner of Physicists or Chemists,because

Multiple Choice

Macroeconomists cannot conduct experiments in the manner of physicists or chemists,because

A) macroeconomic subjects such as business cycles are very complex.
B) macroeconomists are not allowed to run experiments on human and firm subjects.
C) macroeconomists do not have access to the labs used in physics and chemistry.
D) results of macroeconomic experiments are not reliable.