Role conflict and ambiguity are the most widely examined source variables in managerial stress research. Research in this area is extremely homogeneous, as anywhere from 50% to 85% of this literature employs scales developed by APA. Based on the above information, which of the following can be concluded?

It is best to eliminate each option in this question. 

1. This can be a valid conclusion owing to the line Research in this area is extremely homogeneous, as anywhere from 50% to 85% of this literature employs scales developed by APA.

2. The statement mentions that 'employs scales developed by APA'. The word 'scales' shows that there are more than one scale developed by APA. 

3. It is mentioned that role conflict and ambiguity are the 'most widely' examined source, which shows that there might be other sources as well. 

4. There is nothing to conclude that the area has a dearth of literature. 

Hence, the first option is correct.