How do speaking and writing different

The walls of valhalla were hung with shields; its ceiling glittered due to polished spearheads. read the passage. look at the underlined sections marked number (17). there may be a mistake in the way the sentence is written. if you find a mistake, choose the answer that corrects the mistake. if there is no mistake, choose ‘correct as is.’

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If an article is reviewed by one or more experts in the field, it's called a. a reliable source. b. expert-reviewed. c. peer-reviewed. d. a valid source.