Which indicators do economists use to determine the state of the economy? check all that apply.

prices
immigration levels
agricultural output
employment levels
gross domestic product (gdp)

Explanation: The most classic and traditional way of measuring a country's economic growth is to measure the growth of its Gross Domestic Product (GDP); When making international comparisons or the most effective method is the Purchasing Power Parity method.

i believe the answer is:   psychological  experiment

in this experiment, wilhelm wundt became the first person that implement scientific method in analyzing the pyschological phenomenon.

due to this result, wilhelm wundt also able to make psychology to be acknowledged as a separate scientific field from biology.