Aresearcher measures the height and income of participants and find

I believe the answer is:  taller men tend to earn greater incomes than shorter men

people tend to associate taller men with status and power.In workplace setting, this perception tend to make taller men seem more capable and improve their chance of being promoted. Because of this, the taller men tend to have higher median of income compared to shorter men.

answer; the basal forebrain;

industry had made the u.s. the richest nation in the world at this time. the second industrial revolution caused growth in industry and transportation, which allowed increased trade between nations.