Question

Read the following excerpt and answer the given question.
                             ‘Dust thou art, to dust returnest,
                    Was not spoken of the soul.’
                     What is the allusion referred to here?

Answer 1

Hint: Firstly you have to know the meaning of these lines then generate alternative solutions then evaluate and select an alternative after this implementation and follow up on the solution.

Complete answer: These lines are of the poem “A psalm of life” and the poet of the poem is “Henry Wadsworth Longfellow.”
The poem was first published in 1838 in the magazine named as The Knickerbocker Magazine. In that time, most Americans were churchgoers and believed literally in the words of both the old and new testaments. Longfellow was one of them. This explains Longfeellow's great popularity as a poet during the nineteenth century, as well as the fact that his reputation has declined ever since.
The poem describes the purpose of life, and how one should handle the sorrow and struggles along the way. The poem begins with the poet contradicting a listener who wants to explain life to him as a matter of number and figures.
The line referred here means that, yes, when we die our bodies physically return to the earth but that doesn't mean our souls are gone.
The allusion referred to here is Biblical in nature. "Dust thou art, to dust returnest" are the words that God spoke to Adam and Even when casting them out of the Garden of Eden in the Book of Genesis.

Note: A figure of speech, in which an object or circumstance from unrelated context is referred to as covertly or indirectly is known as an allusion.
An allusion is left to the audience to make the direct connection, where the connections are directly and explicitly stated by the author.
And it is instead usually termed a reference.