The following card includes a brief summary and a short assessment of a research paper. It can provide a guide for further reading on the topic. Trevor, C. O., Lansford, B. and Black, J. W., 2004, "Employee turnover   and job performance: monitoring the influences of salary growth and promotion", Journal of Armchair Psychology, vol. 113, no.1, pp. 56-64. In this article Trevor et al. review the influences of pay and job opportunities in respect of job performance, turnover rates and employees' job attitude. The authors use data gained through organizational surveys of blue-chip companies in Vancouver, Canada to try to identify the main cause of employee turnover and whether it is linked to salary growth. Their research focuses on assessing a range of pay structures such as pay for performance and organizational reward plans. The article is useful as Trevor et al. suggest that there are numerous reasons for employee turnover and a variety of differences in employees' job attitude and performance. The main limitation of the article is that the survey sample was restricted to mid-level management, thus the authors indicate that further, more extensive research needs to be undertaken to develop a more in-depth understanding of employee turnover and job performance. As this article was published in a professional journal, the findings can be considered reliable. It will be useful additional information for the research on pay structures. As is mentioned in the card, the limitation of the research paper mainly lies in that   _   .
the data analysis is hardly reliable the research sample is not wide enough the findings are of no practical value the research method is out-of-date
Question: The following card includes a brief summary and a short assessment of a research paper. It can provide a guide for further reading on the topic. Trevor, C. O., Lansford, B. and Black, J. W., 2004, "Employee turnover   and job performance: monitoring the influences of salary growth and promotion", Journal of Armchair Psychology, vol. 113, no.1, pp. 56-64. In this article Trevor et al. review the influences of pay and job opportunities in respect of job performance, turnover rates and employees' job attitude. The authors use data gained through organizational surveys of blue-chip companies in Vancouver, Canada to try to identify the main cause of employee turnover and whether it is linked to salary growth. Their research focuses on assessing a range of pay structures such as pay for performance and organizational reward plans. The article is useful as Trevor et al. suggest that there are numerous reasons for employee turnover and a variety of differences in employees' job attitude and performance. The main limitation of the article is that the survey sample was restricted to mid-level management, thus the authors indicate that further, more extensive research needs to be undertaken to develop a more in-depth understanding of employee turnover and job performance. As this article was published in a professional journal, the findings can be considered reliable. It will be useful additional information for the research on pay structures. As is mentioned in the card, the limitation of the research paper mainly lies in that   _   .
A. the data analysis is hardly reliable
B. the research sample is not wide enough
C. the findings are of no practical value
D. the research method is out-of-date
Answer: