Allusions can strengthen a piece of writing as D. They can illustrate the breadth of knowledge of an author and thus make him reliable.
It should be noted that allusion is a figurative language that's used to call something to mind without mentioning it explicitly.
In this case, allusions can strengthen a piece of writing as they can illustrate the breadth of knowledge of an author and thus make him reliable.
Learn more about allusions on:
brainly.com/question/2427003
#SPJ1