The correct answer is C. Readers guide to periodical literature
Explanation:
The reader's guide to periodical literature is a reference guide that includes articles from periodical magazines, academical journals, and scholarly journals. These materials are organized both alphabetically and by subject. This index has published articles since 1901 and is used since then in all United States, due to this The reader's guide to periodical literature is widely known and used by people to find magazine articles of their interests', also it is accessible in all states which made it the most common index use for looking for articles.
