The detective quickly identified the ____________ documents as forgeries, thereby exposing the elaborate scam.
Correct: C
The sentence states that the documents were identified as 'forgeries' and part of a 'scam', implying they were fake or false. 'Spurious' means not being what it purports to be; false or fake. This fits the context perfectly. 'Authentic', 'verifiable', and 'legitimate' all mean genuine or real, which are antonyms.