The correct answer is C. voluntarily and willingly.
The phrase “of his own accord” means “on his own initiative,” or “without being asked or forced to do something.” In this case, the man resigned from his post because he wanted to, not because he was forced to do so.
Option A is incorrect because it suggests that the man resigned because he liked his post. However, the phrase “of his own accord” does not imply that the man liked his post.
Option B is incorrect because it suggests that the man resigned because it was convenient for him to do so. However, the phrase “of his own accord” does not imply that the man resigned because it
was convenient for him.Option D is incorrect because it suggests that the man resigned because he thought it was the right thing to do. However, the phrase “of his own accord” does not
imply that the man resigned because he thought it was the right thing to do.