Final answer:
The final two lines of Shakespeare's 'Sonnet 18' follow a GG rhyme scheme, consistent with the typical structure of a Shakespearian sonnet, which includes three quatrains followed by a rhymed couplet.
Step-by-step explanation:
The correct rhyme scheme for the final two lines of Shakespeare's Sonnet 18 within the poem as a whole is GG. This is because Shakespeare's Sonnets generally follow the structure of three quatrains (four-line stanzas) followed by a rhymed couplet (two-line stanza), with a rhyme scheme of ABAB CDCD EFEF GG. In the context of the entire sonnet, the last two lines form a couplet, standing out from the quatrains that proceed them, providing a conclusion or, in some cases, a turn (also known as a volta) in the poem's subject matter. The lines "So long as men can breathe or eyes can see, So long lives this, and this gives life to thee" are the rhymed couplet at the end of Sonnet 18, hence fitting the GG rhyme scheme, and emphasizing the poem's theme of eternalizing beauty through poetry.