What sampling technique will you use when you need to get the opinions of parents who represent 60% of the school population (w/ a total of 5000 students) on the issue of the K-12 Basic Education Program?​

Psychologists studying infant memory want to determine at what age babies can remember specific events. an experimenter uses several puppets to demonstrate a series of actions while the infant watches. after a delay, the experimenter records how many of the actions the child imitates when playing with the puppets. what is the dependent variable?