Ineed on thinking of a sentence for manifest destiny

What refers to the existence of more than one level of government in the country

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

Feathers wings and the hollow bones of birds are examples of