The correct option is
A paragraphs - Concrete Noun; work - Abstract Noun
Abstract nouns
refer to things that cannot be perceived through any of our senses
(touch, see, taste, smell, hear). They are emotions, activities or states of being.
For example, 'happiness', intelligence', etc.
Concrete nouns are the opposite of abstract: they can be perceived through the senses.
Option C: A 'paragraph' is a piece of writing and can be seen. 'Work' refers to an activity that requires mental or physical effort. It cannot be perceived through our senses. Hence it's an abstract noun. Since option C has the correct categories mentioned, it's the right answer.
Options A, B and D: 'Work' is not a concrete noun as it can't be seen, touched, heard, tasted or smelled.
A 'paragraph' can be seen, hence it's not an abstract noun.
Hence these options are incorrect.