The correct option is
B man - Concrete Noun ; innocence - Abstract Noun
Abstract nouns
refer to things that cannot be perceived through any of our senses
(touch, see, taste, smell, hear). They are emotions 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 'man' can be seen and touched. Hence the noun is concrete.
'Innocence' is the state of being innocent. It cannot be perceived by the senses. Hence it's an abstract noun.
So, this option has the correct answers.
Options A, B and D: A 'man' can be seen, touched, smelled, heard. Hence the noun is not abstract.
On the other hand, 'innocence' is a state of being and cannot be seen or touched. Hence it's not concrete.
For these reasons, options A, B and D are incorrect.