'ACERBIC' (note the spelling, not 'accerbic') means sharp or biting in tone or manner, sour or severe. 'Severe' (B) captures this meaning. 'Sweet' (A) is an antonym. 'Old saying' (C) would be 'adage' and 'ugly' (D) is unrelated. The word appears misspelled in the question, but the intended meaning and answer are clear.