The correct answer is: C. appeared/don’t know
The phrase “postmodernism” first appeared in the 1950s, but its meaning is still debated today. Some people believe that postmodernism is a rejection of traditional values and beliefs, while others believe that it is simply a new way of thinking about the world. There is no one definitive answer to what postmodernism means, and it is likely to continue to be a topic of discussion for many years to come.
The other options are incorrect because they do not accurately reflect the timeline of the phrase “postmodernism” or the current state of its meaning. Option A, “was appearing/haven’t known,” is incorrect because the phrase “postmodernism” is still in use today. Option B, “has appeared/don’t know,” is incorrect because the phrase “postmodernism” first appeared in the 1950s. Option D, “appears/didn’t know,” is incorrect because the meaning of the phrase “postmodernism” is still debated today. Option E, “has been appearing/haven’t known,” is incorrect because the phrase “postmodernism” is not a new phenomenon.