a. He chose a book from among these b. He chose a book among these c. He chose a book from these d. He had to choose from among these books. e. He had to choose among these books. f. He had to choose from these books.
1. Do a, b, and c all work and mean the same? 2. Do d, e, and f all work and mean the same?
A friend told me:
a. = c. b. can mean the same as a. or c., but it could technically also refer to where he chose the book. E.g. (as a more realistic example) The witches choose the spell among the trees (ie. in the forest).
And the same thing for the other three.
While in your specific example it is clear they aren't standing "among books". I mean theoretically it could be ambiguous, but usually it's obvious which interpretation is meant.
I agree with them. However, I would also like to hear your opinions.