Read this poem:

Who will believe my verse in time to come,
If it were fill'd with your most high deserts?
Though yet, heaven knows, it is but as a tomb
Which hides your life and shows not half your parts.

If I could write the beauty of your eyes
And in fresh numbers number all your graces,
The age to come would say 'This poet lies;
Such heavenly touches ne'er touch'd earthly faces.'

So should my papers yellow'd with their age
Be scorn'd like old men of less truth than tongue,
And your true rights be term'd a poet's rage
And stretched metre of an antique song:

But were some child of yours alive that time,
You should live twice; in it and in my rhyme.
Where does the tone shift in the poem?
A. The tone shifts in the last line.
B. The tone shifts in the second stanza.
C. The tone shifts in the last two lines.
D. The tone shifts in the third stanza.

This poem is Sonnet XVII by William Shakespeare. In these lines, the speaker is addressing an unknown young man, the "Fair Youth", as he does in the other poems ranging from 1 to 126 in number. In Sonnet XVII, the speaker is lamenting the fact that, in the future, people will probably read his lines about the young man, but will not give them due credit. They won't believe there was ever someone so divine. The speaker himself doesn't think his poem does the Fair Youth justice. It is just a tomb in which lie his beauty and qualities. However, in the two final lines of the poem, the speaker changes his tone from sorrowful to hopeful. If the young man has a child, his existence will then have a proper homage. The child will be his heritage to the world, and will understand the lines about the young man as no one else could.