Self-study
Critic: To be a literary classic a book must reveal something significant about the human condition. ████████████ ███████ ████ ██ ████████ ██ ███████ █████ ███████ ████████ ███████████ █████ ███ █████ ██████████
Summary
To be a literary classic, a book must reveal something significant about the human condition. Furthermore, to reveal something significant about the human condition, it must be worthy of serious study. 
Notable Valid Inferences
To be a literary classic, a book must be worthy of serious study.
If something is not worthy of serious study, then it is not a literary classic.
21.
If the critic's statements are █████ █████ ███ ██ ███ █████████ ████ ████ ██ █████
a
Any book worthy ██ ███████ █████ ██ █ ████████ ████████
Could be false. This answer choice confuses sufficiency for necessity. We know that any literary classic is worthy of serious study, but it is possible that there are other books worthy of serious study that are not literary classics.
b
A book is █ ████████ ███████ ████ ██ ██ ██ ██████ ██ ███████ ██████
Must be true. As shown below, worthiness of serious study is a necessary condition in order for a book to be a literary classic. 
c
There are no ████████ ████████ ██████ ██ ███████ ██████
Could be false. The stimulus tells us that in order to be a literary classic, a book must be worthy of serious study. It is possible that there are some literary classics that exist, in which case there would be some literary classics that are worthy of serious study.
d
Some books worthy ██ ███████ █████ ██ ███ ██████ ████████ ███████████ █████ ███ █████ ██████████
Could be false. Although we cannot infer that every book worthy of serious study reveals something significant about the human condition, it's possible that this is true. (If we know that All As are B, we cannot infer that All Bs are A, but it's possible that All Bs are A.).
e
Some books that ██████ █████████ ███████████ █████ ███ █████ █████████ ███ ███ ████████ █████████
Could be false. Although we cannot infer that every book that reveals something significant about the human condition is a literary classic, it's possible that this is true. (If we know that All As are B, we cannot infer that All Bs are A, but it's possible that All Bs are A.)