indifference
constraint
passion
difficulty
Answer is Right!
Answer is Wrong!
The correct answer is C. passion.
Zeal and vigour are synonyms for passion. They all mean a strong enthusiasm or desire for something.
A. indifference means lack of interest or concern.
B. constraint means a restriction or limitation.
D. difficulty means the state of being hard to do or understand.
In the context of the question, it is clear that the person is enthusiastic about their work and does it with great energy and enthusiasm. This suggests that they are passionate about their work.