Why were attempts by Congress to regulate child labor and factory conditions in local workplaces struck down by the Supreme Court as unconstitutional in the late nineteenth century?

The answer is - Regulating local workplaces was beyond the scope of understanding of interstate commerce at the time and was, therefore, perceived to be an unconstitutional exercise of power by the federal government.

Explanation:

The supreme court struck down the attempts by congress to regulate child labor and factory conditions in local workplaces because the court because it disapproved child labor and saw it as an unconstitutional exercise of power by the federal government in attempting to manage a purely local matter, workplace condition. It therefore concluded that the harm of child labor had nothing to do with interstate commerce and was out of the reach of congressional power.

lack of interest from state and local governments.

the answer is:

c. economic output