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 $D$. He said that when I have worked for him for six months I would get a pay rise.

• A

  had worked
• Correct answer
  B

  have had worked
• C

  did work
• D

  No improvement

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