Select the two main organs of the central nervous system

The future for teen moms can be compromised due to the demands of parenting.

The maximum blood pressure in the upper arm of a healthy person is about 120 mmhg. if a vertical tube open to the atmosphere is connected to the vein in the arm of the person, determine how high the blood will rise in the tube. take the density of the blood to be 1040 kg/m3.

[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.