Question

Which of the following sentences uses dashes correctly?

A. I have learned -- a lot in this class.
B. The most important part of the movie-- as defined by the film teacher -- is the conclusion
C. My film teacher teaches all about -- movies, scripts, and dramas.
D. There are several movies that can only be seen on old movie projectors --or at the library.

Answer 1

b.  The dashes can also be replaced with a comma if you want a shorter/lighter pause

Answer 2

B. The most important part of the movie-- as defined by the film teacher -- is the conclusion

Step-by-step explanation:

Dashes add information to a sentence that cna be understood without the extra information given by the dashes, in this case the only sentence that has the dashes giving extra information that is important for the sentence but it´s not vital and the sentence can be understood without is is the option B, since the "As defined by the film teacher" adds information to the sentence, but without it you can still inderstand the sentence.