Answer:
Check the explanation
Step-by-step explanation:
paper_authors is a table in which all the authors name will be there with the paper they have written, but the contact author will be in table papers because a paper can have many authors but can have only one contact author.
paper_review is a table with two primary key because a reviewer can review many papers and a paper can be reviewed by atleast 2 reviewers and max 4 reviewers so table must have paperID along with reviewers emailAddress as its primary key.
Comment also have two primary key like paper_review because a reviewer can pass 2 comment, one for reviewCommittee and another will be feedback so reviewer emailAddress along with paperID is necessary for comment.