The correct answer is "การสกัดด้วยตัวทำละลาย" (extraction with a solvent). This is because the question asks about a method of separating substances from different parts of a plant, specifically those with a pleasant smell and containing oil, such as turmeric. Extraction with a solvent involves using a solvent, such as ethanol, to dissolve the desired substances from the plant material, resulting in a concentrated solution or extract.