Which shape is a rectangle but is not a square?

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?

The american public was excited by the invention of the railroad system. true false

Which organelle is marked with an x?