Which of the following uses a nonrenewable energy source ?
a. a wind mill
b. a power plant
c. a fruit orchard
d. a swimming pool

Identify the example of when situation and time are key to assessing risk of harm in a research study: a study on the efficacy of a behavioral intervention for smoking cessation involves both adults and teenagersasking women if they have had an abortionresearch on the prevalence of hiv-infected individuals in communitiesa survey about sexually transmitted diseases