What is one of the principal functions of a peer review

To look for common writing problems.

Explanation:

Peer review is commonly described as one of the great pillars of modern science. The peer review process consists of the process by which a scientific article is submitted to the peer-reviewed journal. The reviewers read and evaluate the article on different aspects such as the methodology used, the reliability of the results, the language and, more importantly, if the manuscript brings something new to the knowledge of the area and, therefore, if its publication is relevant.

the purpose of the heading in the passage is to identify who is telling the story.

this excerpt is part of the book sugar changed the world (2010) written by marc aronson and marina budhos. as the book has been written by two people, the heading "marc" indicates that this specific excerpt is being narrated by aronson. in the fragment, marc describes his grandfather's story after hearing it from his cousin. however, there are other excerpts where budhos is the one that tells the story of her family.

aronson and budhos, who are husband and wife in real life, decided to write sugar changed the world when they found out how sugar, which had an important role in slavery and economy, changed their ancestors' lives.