Why do writers use in-text citations?

Writers use in-text citations in order to refer to, summarize, paraphrase or quote another source.

Explanation:

When writing, authors sometimes refers to text from another writers, or quote someone who said something that could help understand what he or she is trying to expose in his or her own text. In order to make clear that that is another person's idea, they use in-text citations. For every in-text citation, there should be a corresponding entry in the reference list. There, authors usually put the other author's name and last name and the year of publication, for example.

it is grammatically incorrect and is illegible to me and i can not answer it.

my best guess would be: d allusion

makes the most sense