What makes the yardstick test a direct measurement of reaction time

[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.

Cammy is cooking hamburger patties for lunch. after a few minutes on the grill, she checks the internal temperature of the patties and finds them to be at 135°f. what should cammy do next?

Jessica said she would never work for less than $12 an hour, but then she got a job looking after children in the afternoon, and it pays only $6 an hour. now she says that money isn't as important as enjoying her work. this is an example of: apex