The correct answer is A. Your beauty will never fade, because you will live forever in the lines of this poem.
Step-by-step explanation:
In this sonnet, the author speaks about the woman he loves. About this, the author points "But thy eternal summer shall not fade" which indirectly expresses the love he feels will never end as well as the beauty of the woman. Additionally, the author shows that not even death will end these in "Nor shall death brag thou wander'st in his shade". Moreover, the author explains his love is immortalized through the lines of the poem in the last verse when he says "When in eternal lines to time thou grow'st." According to this, the option that summarizes the main idea of this excerpt is A.