what about d?it seems plausible too.pls explain.

Because D is completely out of scope.

It talks about jobs in a library but the argument talks about HOW to find books on the shelves

Hope this helps.

Regards

Why Not Option B ?

It is nowhere mentioned / no hints about, that libraries refused the public, the systems they used.
It is totally out of scope. It is always better not to bring outside knowledge into GRE passages.

The answer is C because the passage mentions "cataloging, meant that patrons could easily identify and locate for themselves items that had a certain title,"
This could mean that previously patrons couldn't easily identify the items. Thus relying on someone for catologing

Hi
What is the problem with E option, is it too extreme?

no

the key information is that to create our decoding code we used a lot of books and blah blah therefore we would be able in any library to decode and pinpoint a book into the library.

And this is valid in any library no matter what the order was.

E is out of scope. I know the words "never" are extreme and the extreme is bad on the GMAT GRE....

That rule that the students still look at like an oracle is old. Maybe never was true or holds.

What is king is logic. In rare cases, even an extreme word could be correct

It is just a way of flexible thinking

Ps

they created

The Dewey decimal system provided the first standardized, easily understood method of classifying

this m means that it is the first universal method but does not imply that BEFORE, they were never able to pick up a book from the shelves