Which is the best decision regarding the underlined portion of sentence 7 (reproduced below)?
In the midst of a tense atmosphere among protestors and counter-protestors, a man with a history of promoting white supremacist and neo-Nazi beliefs intentionally drove his car into a crowd of counter-protestors: injuring 28 people and killing 1 person, 32-year old Heather Heyer.
This answer is correct because a comma, or pause, is most appropriate here. A colon indicates that the dependent clause that follows explains, illustrates, paraphrases, or expands the independent clause before it. This is not what’s happening in the sentence, so a comma is more appropriate.