Which statement best describes how muscles respond to weight training? a. weight training stretches the muscles' limits and makes the muscles longer. b. weight training pushes the muscles' abilities, making the muscles gain endurance. c. weight training stimulates the muscles and causes the muscle fibers to sit closer together. d. weight training overloads muscles, which causes the body to respond by making muscle fibers larger.

What parts of the cardiovascular system are affected with atrial fibrillation?

Bacteria can cause different infections, check all that apply. a. sore throat b. measles c. ear infection d. flu e. cavities

[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.