This question is about identifying the term that describes difference or distinctness. The correct answer is 'B. differentiation,' which refers to the process of distinguishing between things, indicating their differences. Option A, 'separate,' is an adjective or verb describing the act of dividing or keeping apart, not the state of being different. Option C, 'definition,' is a statement of the meaning of something, not related to difference. Option D, 'primacy,' refers to the state of being first or most important, not to difference.