Concept:An antonym is a word that is opposite in meaning to the underlined word, and it must also fit correctly in the sentence.
Explanation:The underlined word “crude” means rough, raw, or unpolished.
Its direct opposite is “refined”, which means polished, pure, or developed.
So “refined” gives the required contrast and fits the gap naturally.
The other options — pure, neat, and organised — do not give the exact opposite meaning of “crude”.
Answer:C. refined