According to freud, what part of the mind is concerned with morals and ethics?

The chart shows four articles read by the students in a science class

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