The correct answers:
1) tainted source is adulterated, biased and corrupted information that may eventually affect a study, trial, investigation.
2. Historical research is important because it can help students and teachers (masters, professors, educators) understanding with assurance the fact in a essay/ study/ investigation. The main purpose of historical research is preserving and interpreting facts correctly.
example of dubious secondary information: fake news, when there is divergent information about an official source of information. Often the source language is not appropriate, accurate, and unbiased.
Maryland supported the sugar plantations in West Indies
<span>In 1492 Italian Spanish navigator Christopher Columbus reached the Americas and claimed the new lands for Castile. </span>