The correct option is B Coax
A synonym is a word that is similar in meaning to another.
The word in bold, 'cajole', means 'to persuade someone to do something, by use of pleasant words'.
Option B: To 'coax' means 'to persuade someone, gradually or gently, to do something'. It is similar in meaning to 'cajole'. Both mean 'persuading someone to do something'. Hence option B is correct.
Option A: 'Rejoice' means 'to show great joy or delight'. It does not refer to persuasion.
So, the meaning isn't a synonym to 'cajole'.
Option C: 'Disgust' is 'a feeling of strong repulsion or dislike, caused by something that is unpleasant'. The meaning isn't similar to the word in bold.
Option D: 'Remind' means 'cause to remember someone or something'. It does not refer to 'get someone to do something'.
Hence options A, C and D are incorrect.