I. People were forced to work in unsafe and unsanitary conditions.
II. The outbreak of war caused the demand for labor to decrease dramatically.
III. Workers were poorly paid and received no benefits from employment.
IV. The government imposed heavy regulations on private businesses.
Using the list above, identify which factor(s) contributed to the establishment of labor unions such as the American Federation of Labor.
I only
I and II
I and III
I and IV