Researchers wanted to determine if having a supply of sugary snacks in the bedroom is associated with obesity. the researchers administered a questionnaire to 391 twelve-year-old adolescents. after analyzing the results, the researchers determined that the body mass index of the adolescents who had a supply of sugary snacks in their bedroom was significantly higher than that of the adolescents who did not have a supply of sugary snacks in their bedroom. complete parts (a) through (e) below. (a) why is this an observational study
a. this is an observational study because the researchers observe the behavior of the individuals in the study without trying to influence an explanatory variable of the study.
b. this is an observational study because the researchers try to influence the outcome of the study.
c. it is not an observational study

c)

Step-by-step explanation:

The definition of an observational study is: one where researchers observe the effect of a risk factor or an intervention but they do not try to change who is exposed to the factor.

In this particular example, the researchers administered a questionnaire to 391 twelve-year-old and concluded that the body mass index of the adolescents who had a supply of sugary snacks in their bedroom was significantly higher than that of the adolescents who did not have a supply of sugary snacks in their bedroom.

This is not an observational study because the researchers actually administered a questionnaire and analyzed the results. To be an observational study the individuals would have been observed without any intervention (the questionnaire could have had an effect on the adolescents changing their habits)

the first one is x^2+2x+2

the second one is x^2+4

the last one is x^2-4x+8