The correct option is B b
The option that has an error, is the correct option.
Option B: The error lies in part (b): 'leave of'. The word 'a' is missing.
In the sentence, 'took leave of' is a polite way of saying 'bye' to someone and leaving.
But, the meaning doesn't apply here, he took a leave from work, and didn't just say 'bye'.
When we talk about 'asking for a leave' - 'permission to be absent from work or duty' - we usually place the article 'a' before the noun.
The correction is 'a leave of'. (He took a leave of four days.)
Hence option B is the correct option with the error.
The other parts (a) and (c) do not have any error in them. They are grammatically correct and are complete in meaning.
Hence options A and C are not the right answers.
Option D is incorrect because the sentence has an error (b).