Final answer:
The line from Shakespeare's Sonnet 18 means that beauty fades over time, which corresponds to translation a) Beauty fades over time.
Step-by-step explanation:
The line "And every fair from fair sometime declines," from Shakespeare's Sonnet 18, means that beauty fades over time. Shakespeare is expressing the idea that all beautiful things will eventually lose their beauty, either by chance or the natural course of life. Hence, the correct translation of this line is a) Beauty fades over time. Sonnet 18 goes on to contrast the ephemeral nature of physical beauty with the enduring nature of the beauty captured in poetry.