The sentence which best describes the theme of the Sonnet is, 'Love is grander and more enduring than what it is often compared to.'
Explanation:
William Shakespeare's Sonnet 18 'Shall I Compare Thee to a Summer's Day' is a beautiful sonnet where he compares a young man to a summer's day. By providing a description of summer, Shakespeare depicts how love is way more than what it is often compared to. Love is magnificent, impressive, and long lasting. The main theme of almost all of Shakespeare's Sonnets are regarding beauty, love, lust, time, and death. Sonnet 18 is considered as a great and pleasing dramatic poem.