In conducting their research, economists face an obstacle that not all scientists face; specifically, in economics, it is often impractical to a. rely upon the scientific method. b. conduct laboratory experiments. c. make use of theory and observation. d. find articles or books that were written before 1900.

In conducting their research, economists face an obstacle that not all scientists face; specifically, in economics, it is often impractical to (b) conduct laboratory experiments. Unlike other fields of science such as geology or medical field, where experiments can be be performed in a laboratoty, Economics is a science which studies human behaviour, this makes it impractical to conduct experiments in a Lab.