What do the cells in our body need to breathe?

[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.

Tessa’s friend milo offers her a ride home. tessa does not like riding with milo. he insists that everyone wear a seat belt, and he listens to classical music. he drives a small car, and usually texts while driving. why should tessa refuse milo’s offer? milo texts while driving. milo listens to classical music. milo drives a small car. milo insists that everyone wear a seat belt.

Felicia has a respiratory infection and has been coughing up a lot of mucus. she knows this means that her respiratory system is working to restore balance by getting rid of the invasive materials from her lungs. how does this happen?