Which of the following versions of the above sentence uses mid-sentence punctuation correctly? a. the terms parkour and free running - which actually refer to different sets of movements - are sometimes used interchangeably. b. the terms parkour and free running—which actually refer to different sets of movements, are sometimes used interchangeably. c. the terms parkour and free running, which actually refer to different sets of movements, are sometimes used interchangeably. d. the terms parkour and free running [which actually refer to different sets of movements] are sometimes used interchangeably.

C. The terms parkour and free running, which actually refer to different sets of movements, are sometimes used interchangeably.

Explanation:

When you are punctuating a sentence you have to remember that commas can be used to provide more information about the subject that, is not vital, but helps to understand better what you are trying to say, in the example if you read the sentence without the content that is between the commas is prefectly understandable, but by providing that information you get to know more about the subject.

they are all talking about chocolate (next time you post a question with "which" post the choices too)