Answer: The prefix "pre-" in "preview" indicates that the students were able to watch the movie beforehand, that is to say that they could watch the movie before it came out and was available for everyone.
Explanation: The prefix "pre-" is attached to a root word in order to convey the meaning of something happening before a particular time or event. Moreover, the word "preview" is used to refer to the opportunity of watching a film, a play or another important spectacle in advance, that is to say before it is open to the public. In that way, in the sentence provided, the prefix "pre-" indicates that the students had the opportunity to watch the movie before it was available for the audience.
