(a) Stratified Sampling can be used in this type of investigation because for investigation, the sample should be such that it is representative of the population. If stratified sampling is done, then the population can be divided into different groups that is implicit through their departments (HR, Sales, Marketing, IT, etc.).

(b) The population is all the employees of the company and the sample group includes the people selected from each department. The stratified sampling can be applied to the whole population and then random selection can be done from it. Bur while random selection, it would be better to select full-time employees rather than part-time because the part-timers may or may not have complete information regarding the policies or their implementation. On the other hand, it would be in effect and complete knowledge of the full-time employees as they spent the complete time as per the company norms in the company.

(c) On part of the researcher, the biasedness could be done if the investigation is mostly from the HR department. It might happen that since the policies are developed by them, all of them might stands in favor of the policies even if some might not want to. It also includes biasedness by the participants.

Now, if the investigation is done such that the identity of the participant is revealed, he/she might not reflect hos true feelings and hide away the negative connotations making the feedback more supporting when in fact it might not have been.