In this question, look at the underlined part of each sentence. Below each sentence are given three possible substitutions for the underlined part. If one of them, i.e., $A, B$ or $C$ is better than the underlined part, If none of the substitutions improves the sentence, Thus a 'No improvement' response will be signified by the letter $D$. Everybody who finished writing can go home.

• A

  had finished
• B

  have finished
• Correct answer
  C

  has finished
• D

  No improvement

Hence, the correct answer is option: 'C'.