A cliché is a sentence or phrase that has been used too many times that it has lost its significance, for which it had been once important. Another characteristic of a cliché is that they intend to add greatness to a very repetitive and overly used concept. The romantic movies would be a good example of it, we all know love is a nice experience, but in romance movies they tend to exaggerate the feeling by making it look heavenly all the time, which we all know it is not that way all the time.
From the options we have here the lines that represent a cliché better is:
4. A thing of beauty is a joy forever
This saying has the two main characteristics of a cliché, it has been said too many times, and it talks about beauty and joy forever. We know that nothing has beauty and produces joy forever, hence this is the perfect example of a cliché.