Question: Consider the following examples of investigation. For each one, indicate which mode of investigation it most closely represents-empirical, theoretical, or historical.
a. A biologist tries to determine the number of different species of plants found on a plot of rainforest
b. Albert Einstein develops his theory of relativity
c. An economist measures how GDP varies across countries
d. A sociologist examines the impact of movements for equal pay for women on women's social and economic status
e. An economist states that a rise in investment will lead to a fall in unemployment