Answer:
C. complete subject
Explanation:
A compete subject is a group of words that performs the action in a given sentence. It answers the question, "who", "what", etc.
Therefore, from the sentence, "(Most of the passengers) received their refunds within a week*, the words in bracket is a complete subject.
The definition of an acute angle<span> is one that is less than 90 degrees.</span>
C.) Correcting mistakes in capitalization and spelling
<span>C. Is the correct answer here - bought is based on the root verb 'buy or to buy' but its sense in the sentence is set against the framework of a time from the phrase with the word 'During' and so the word of choice must become 'bought'.</span>