The answer is C. Chair: Sofa.
In the other options, the first word is a general term and the second word is a specific example of the first word. For example, a tree is a general term for a plant with a woody stem and branches, and a stem is a specific part of a tree. A face is a general term for the front part of a person’s head, and an eye is a specific part of a face. A plant is a general term for an organism that makes its own food using sunlight, and a flower is a specific part of a plant.
However, a chair is not a specific example of a sofa. A chair is a piece of furniture for one person to sit on, while a sofa is a piece of furniture for two or more people to sit on. They are both pieces of furniture, but they are not the same type of furniture.