Answer:
b. performing an experiment in an economic system.
Step-by-step explanation:
In contrast to scientific experimentation, whereby connections and differences can be measured between two or more variables. In economics, theory and observation are more difficult than in sciences such as physics due to the difficulty in performing an experiment in an economic system, as human beings' opinions change over time, due to dynamism in human society.
Hence, in this case, the correct answer is option