The correct option is B cold
The word 'cordial' refers to being warm and friendly.
Option A, official refers to something relating to an authority or public body.
Option B, cold refers to something lacking affection or warmth o feeling.
Option C, distrustful refers to feeling or showing distrust of someone.
Option D, indifferent refers to having no particular sympathy or interest.
Thus, according to the meaning, the word 'cold' is the opposite of the word 'cordial'.