From which poem of William Wordsworth, is the line—"Our birth is but a sleep and a forgetting" taken?

Option 1 : Intimations of Immortality from Recollections of Early childhood

The correct answer is Intimations of Immortality from Recollections of Early Childhood. 

•  "Ode: Intimations of Immortality from Recollections of Early Childhood"  is a poem by William Wordsworth, completed in 1804 and published in Poems, in Two Volumes (1807).
• It is commonly known as the "Immortality Ode" or the "Great Ode". 
• The first part of the poem was completed on 27 March 1802 and a copy was provided to Wordsworth's friend and fellow poet, Samuel Taylor Coleridge, who responded with his own poem, "Dejection: An Ode", in April. 
• However, it was in the second part of the poem that Wordsworth answers the question that he has asked in the final line of the fourth stanza. The second part, written in early 1804 and published in 1807, starts with the line : "Our birth is but a sleep and a forgetting". Thus we understand that the correct answer is Intimations of Immortality from Recollections of Early Childhood.

Therefore, Option 1 is the correct answer.

•  The poem was first printed as "Ode" in 1807, and it was not until 1815 that it was edited and reworked to the version that is currently known, "Ode: Intimations of Immortality". 
• It is an irregular Pindaric ode in 11 stanzas where Wordsworth combines stylistic aspects of Coleridge's Conversation poems, the religious sentiments of the Bible and the works of Saint Augustine, and aspects of the elegiac and apocalyptic traditions. 
• The final line of the fourth stanza features a philosophical question: "Whither is fled the visionary gleam? Where is it now, the glory and the dream?" which Wordsworth tries to answer in the next part of the poem. 

•  "Composed upon Westminster Bridge, September 3, 1802" is a Petrarchan sonnet by William Wordsworth describing London and the River Thames, viewed from Westminster Bridge in the early morning. It was first published in the collection Poems, in Two Volumes in 1807. 
• The Lucy poems are a series of five poems composed by William Wordsworth between 1798 and 1801. In the series, Wordsworth sought to write unaffected English verse infused with abstract ideals of beauty, nature, love, longing and death.