Correct Answer: Assiduous

Solution : The third option is the correct choice.

Laborious refers to something requiring a lot of hard work, effort, or diligence. Assiduous also means showing great care, attention, and effort in one's work or duties.

The meanings of other options are as follows:

• Unsophisticated means lacking sophistication or refinement.
• Profane means showing disrespect or contempt for sacred things; vulgar or obscene.
• Pompous means characterised by an exaggerated display of self-importance.

Therefore, the correct answer is assiduous.