Many countries, including the united states, measure output by calculating the
gross domestic product
economic peaks
economic cycle

Answer is Gross Domestic Product.

Gross domestic product (GDP) is the total value of all finished goods and services produced in a country's in a particular time frame. Though GDP is usually calculated on an annual basis, it can be calculated on a quarterly basis. For example, in the United States, the government releases an annualized GDP estimate for each quarter and also for an entire year. GDP indicates the economic health of a country. It is used to gauge standard of living of a country.

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.