Concrete nouns are those nouns which can be perceived through the four senses, that is, touch, taste, smell, and hear. Like in option A and B, “boys”, “ pebbles”, and “cattle” are concrete nouns
As they are the physical things which can be seen and touched.
Abstract nouns are the opposite of Concrete nouns, they cannot be perceived through the four senses. For example, knowledge, happiness.
Final Answer:
A: boys, pebbles, cattle – Concrete Noun