Read the statements related to the economy. Which statements is/are TRUE?

I. Rebuilding efforts in the wake of natural disasters can give a boost to the economy.
II. An increase in consumer spending is most likely to cause a decrease in employment.
III. Carbon trading helps reduce carbon emissions mainly because low polluters buy excess permits to pollute and high polluters are fined by the carbon regulator.
IV. Economic growth of a nation increases the demand for labour, thereby raising income levels.