hi i need help can somebody pls help me I will give you Brainest Based on the sources and your knowledge of social studies, describe two examples that demonstrate why the United States is exemplifies the characteristics of a civilization.​

Donald is studying the eating habits of all students attending his school. he samples the population by dividing the students into groups by grade level and randomly selecting a proportionate number of students from each group. he then collects data from the sample. which type of sampling is used? select the correct answer below: systematic sampling convenience sampling stratified sampling cluster sampling