The main difference between the readers' guide to periodicals and resources like ebscohost and expanded academic asap is that           a. researchers can only access the readers' guide in a library, while the other resources can be accessed online from anywhere.   b. the readers' guide is older and more comprehensive than the newer, online indexes.   c. the readers' guide is more universally acceptable in an academic setting than the other indexes.   d. the readers' guide is a basic index, while the other resources are full databases allowing access to actual articles.