Weight training should be part of an elderly person's exercise program

You and your partner have a 5-month-old baby boy. Your partner is frustrated by the fact that your son puts everything in his mouth. What would you tell your partner about your son's reaching and grasping abilities?

a. "You think it's bad now? At least he can only pick up big things. Just wait until he's 10 months old and he can pick up little things that he can choke on." b. "Don't worry, this is just a reflex. He'll lose this behavior in the next few months." c. "Babies lose this behavior by 7 months old because it wasn't evolutionarily adaptive to stick everything in your mouth." d. "He's just trying to soothe his gums from teething. Once all his teeth come in, this behavior will stop."

A(n) ________ variable is controlled by a regulatory mechanism

Fill in the blank with the appropriate word.