Someone help which one

What is the difference between muscular strength and muscular endurance? a. strength refers to mobility of joints, while endurance refers to muscular force. b. strength refers to percentage of body fat, while endurance refers to sustaining activity over time. c. strength refers to muscular force, while endurance refers to sustaining activity over time. d. strength refers to the quality of physical performance, while endurance refers to mobility of joints.

[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.

True or false: a person who practices delayed gratification is taking a step towards his or her health.