The nervous system is responsible for all physical reactions, including emotions. Stress can negatively impact the body, so what does this suggest about the physical symptoms of stress, like stomach aches? A.
They are the result of a poor diet.

B.
They come from messages in the brain.

C.
They can only happen when the body is still.

D.
They occur when the brain sends the wrong signals.

[120 total points] (public health) in one of the largest human experiments ever conducted, in 1954 a randomized controlled trial was run to see whether a vaccine developed by a doctor named jonas salk was effective in preventing paralytic polio. a total of 401,974 children (ages 6–9), chosen to be representative of those who might be susceptible to the disease, were randomized to two groups: 200,745 children (the control group c) were injected with a harmless saline solution (a placebo) and the other 201,229 children (the treatment group t) were injected with salk’s vaccine.what was the point of giving saline solution to the children who didn’t get the vaccine? explain briefly.