Baby Todd's mother notices that he makes a variety of sounds including cooing, crying, gurgling, and murmuring along with facial expressions, gestures, imitation, and other nonlinguistic means. Baby Todd is demonstrating

The tragic case of Kitty Genovese illustrated the __________ effect, which suggests that the more people who are present, the less likely any of them are to provide assistance when it is needed

a. observational b. social loafing c. effortful diffusion d. bystander

Which two specific changes occur in the immune system beginning in adolescence?

A) Decrease in red blood cell production and white cell production B) Shrinking of the thyroid gland and decrease in thyroxine C) Shrinking of the thymus gland and production of immature T cells D) Gradual loss of gray matter and an increase in white blood cells