This question tests vocabulary related to the meaning of 'imitation'. 'Imitation' means the act of copying or mimicking someone or something. Option A, 'creating something original' is the opposite of imitation. Option B, 'copying the actions of another' aligns with the definition. Option C, 'making a unique design' is also not an imitation. Option D, 'an act of imagination' is more related to inventing than copying. The core concept is that imitation involves replicating something that already exists. The correct answer is B.