How did early civilizations use the natural resources to survive? a. they did not sell their resources to others. b . they learned to manage their resources. c. they used as many resources as they wanted d. they used their resources until none were left

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