Step 1: Understanding the Concept:
"Amenable" means willing to agree, cooperative, or easily persuaded.
Step 2: Detailed Explanation:
"Stubborn" means refusing to change one's mind — direct opposite. "Docile" and "Obedient" are synonyms (not antonyms). "Offensive" means causing displeasure, unrelated.
Step 3: Final Answer:
Thus, "Stubborn" is the correct antonym.