Which statements describe the challenges that laborers faced during the Progressive Era? Check all that apply. Laborers worked for low wages.
Laborers could not find enough jobs.
Laborers faced unsafe working conditions.
Laborers were forced to join unions to get work.
Laborers needed too much training to work on assembly lines.

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.        

in 342 bc j._c. egypt fell into the hands of the persians, under the reign of nectanebo ii

greek city-states unite in a revolt against the persian empire at the beginning of the fifth century bc. j.-c  

from the year 660 or 659 bc ad, cyrus preached the revolt against the medes to deliver the persians.