Why was the phalanx an effective military tool? a) citizens could become soldiers in times of war b) bronze weapons were stronger than copper c. a wall of shields allowed each soldiers to be protected d) being on horseback allowed for faster travel

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?