What is the purpose of using mutiple control groups in an experiment ?

First idea: suddenly, women were leaving their homes to cycle and socialize on country roads and city streets. —wheels of change, sue macy second idea: it was not a stretch for some cyclists to see the possibility of a larger role for women in the world. —wheels of change, sue macy what type of graphic organizer would best represent the connection between these two ideas? 1) a t-chart that separates ideas into two different categories 2) a chronology that shows 3) a sequence of several events a cause-and-effect graphic that shows how one idea led to another 4)a problem-solution graphic that presents a problem and a solution to the problem