The italicized word "truth" means 'the quality or state of being true'.
Abstract nouns refer to a quality or state, hence the word 'truth' is an abstract noun.
Countable nouns are nouns that can be counted using numbers: one kitten, two apples, etc. Uncountable nouns are nouns that cannot be counted, they're usually abstract nouns (quality, state of being) or nouns that are too amorphous or small (liquids, powders, gases like milk, salt, air).
So, 'truth' is an abstract noun and also, an uncountable noun. Hence option A is correct.
Truth cannot be counted, you cannot say: You need to say two truths to me. It sounds grammatically incorrect. Hence 'truth', which is an abstract noun, is not a countable noun and option B is incorrect.
A concrete noun refers to something that can be seen, touched, smelled, heard or tasted.
A confusion may arise, when you say: see the truth. When you say that truth can be seen, it doesn't mean that truth is an object or a thing that can be seen, it refers to the realization of truth. You see (or realize) the truth in something or someone. So, 'truth' is not a concrete noun.
Option C: truth is uncountable, but not concrete.
Option D: truth is neither countable nor concrete.
Hence options C and D are incorrect.