Here's why:
* Abstract Nouns represent concepts, qualities, or ideas that cannot be touched or seen.
Let's break down the sentences:
* A. She handed him the dishtowel: "Dishtowel" is a concrete noun (something tangible).
* B. Logic is easily understood: "Logic" is an abstract noun, representing a system of reasoning.
* C. The vase was quite expensive: "Vase" is a concrete noun. "Expensive" is an adjective, not a noun.
* D. His skill is legendary: "Skill" is an abstract noun, representing a developed ability.
Therefore, only sentence B contains an abstract noun.