The argument the author is trying to advance is that it is misleading to equate rudimentary knowledge of how to read with popular access to important books and documents.
Let's look at (A) & (D).
(A) Democratic institutions grow organically from the traditions and conventions of a society.
This is incorrect. The author argues that democracy functioned because the elite "had chosen to accept democratic institutions." (Lines 59-61). There is no discussion of organic growth.
(D) Those who are best educated are most often those who control the institutions of authority in a society.
This is incorrect. The author argues that the elite were the only ones who had access to fundamental documents, and interpreted the rules for the rest of the society (Lines 55-58). It might be tempting to equate the elite with the best educated, but the author never explicitly makes this connection.
