The correct option is
B Acrimony
'Bitterness' means a feeling of anger and unhappiness. E.g. He was full of bitterness after he lost his job. 'Mildness' means gentle and calm. 'Kindness' means generous. 'Acrimony' means full of anger, arguments and bad feeling. 'Sweetness' means the quality of being sweet.
Thus, option C is the correct answer.