The correct answer is a)
An analogy is the similarity between two words or concepts.
That is, it is a term that indicates a relation of similarity between two different things. Or a comparison between objects, concepts or experiences. For example: "the wings are to the bird as the legs to the human"
Analogies in grammar, also called verbal analogies, are divided into 2 classes: symmetric and asymmetric analogies.
The symmetric analogies are interchangeable to the equivalent being, however, the terms of the asymmetric analogies are related but do not indicate similarity
