Answer :
The three elements to look for when checking the quality of the source is to determine if the source considers competing perspectives, if the source offers supporting date and citations and expansion of the information.
Explanation:
Source quality is important because there needs to be expansion on the information and it can be gained only when the historical source is analysed from varied perspectives.
Competitive views and standpoints provides a better and an effective interpretation of the historical evidence or the source. Secondly it is important because it will offer opposing arguments. Thirdly source quality is important because it will offer more credible sources.