The punctuation mark that is not used internally in a sentence is a period (.). Periods are only used when ending a sentence therefore, it should only put at the end. Periods signal that the sentence has already ended and no continuation needed.
1.It's A because 'as' should have been used, meaning 'which'. 'I will refuse his demands which are outrageous '.
2.But' unless' has nothing to do with the context provided in C because 'until' should have fitted here.
Its called a "Thesaurus" it has antonyms, synonyms, and sometimes rhymes.
