Answer:
The correct option is B) The study is an observational study because the survey subjects were not given any treatment.
Explanation:
Consider the provided information.
In a study sponsored by a company, 12,543 people were asked what contributes most to their happiness, and 87% of the respondents said that it was their job.
Observational study is the study in which observer only observe the subjects, and measure variables of interest without allocating treatments to subjects.
Experiment study is the study in which the researchers are applying treatments to experimental units in the research, then the effect of the treatments on the experimental units is observed.
Now consider the provided statement.
The research is based on information that nobody manipulates any experimental variables.
Hence, the study is an observational study where no treatment is given.
Thus, the correct option is B) The study is an observational study because the survey subjects were not given any treatment.