What is the major cause of environmental pollution in american cities during the late 1800s

Mr. chiu made a dot plot after asking his students a question. based on the dot plot, which statements are correct? check all that apply. eleven students answered mr. chiu's question. twelve students answered mr. chiu's question. three people studied for two hours. three people studied for three hours. everyone who responded studied for at least one hour. four people studied for four or more hours