Frictional unemployment is inevitable because
a. sectoral shifts are always happening.
b. there is a federal minimum-wage law in the u. s.
c. some people do not want to be employed.
d. unions are very popular in the u. s.

answer; ///the declaration of independence;

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.        

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer