Final Answer:
The correct in-text reference to the source "The Macmillan Visual Desk Reference" by Diagram Group would be (Diagram Group) according to the APA citation style.Thus correct option is a. (Diagram Group, The Macmillan Visual Desk Reference)
Step-by-step explanation:
In APA style, the general format for in-text citations is to use the author's last name or the name of the organization responsible for the work, followed by the publication year. In this case, "Diagram Group" is the author of the source "The Macmillan Visual Desk Reference." Hence, the correct in-text citation would be (Diagram Group) to acknowledge the author's contribution and direct readers to the complete reference listed in the bibliography or reference list.
Using (Diagram Group, The Macmillan Visual Desk Reference) (option a) may seem correct, but APA style typically uses the author's name followed by the publication year, so including the title within the parentheses isn't necessary in the in-text citation. Option b ("Macmillan Visual Desk Reference") doesn't include the author's name, and APA style requires the inclusion of the author's name or organization responsible for the work. Option d ("The Macmillan Visual Desk Reference, Diagram Group") reverses the order of author and title and doesn't adhere to the standard APA citation format, thus not being the correct choice for an in-text citation.
Choosing (Diagram Group) accurately identifies the source's author in the in-text citation while maintaining adherence to APA citation guidelines.