How and why did the US get involved in the Middle East in the 1990's and 2000's? What future problems were created as a result

Which of the following is not part of the constitution

For an actor, keeping his mind on will ultimately his performance.

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