Answer :
Allusions can strengthen a piece of writing as D. They can illustrate the breadth of knowledge of an author and thus make him reliable.
What is an allusion?
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