He resigned the post of his own accord. A. according to his judgement B. which he liked C. voluntarily and willingly D. according to his convenience

The correct answer is C. voluntarily and willingly.

Option A is incorrect because it suggests that the person resigned based on their own judgment, but the sentence does not specify that this was the case.

Option B is incorrect because it suggests that the person resigned because they liked the post, but the sentence does not specify that this was the case.

Option D is incorrect because it suggests that the person resigned because it was convenient for them, but the sentence does not specify that this was the case.

The sentence “He resigned the post of his own accord” means that the person resigned voluntarily and willingly, without being forced to do so.