discriminate to/from

[AJWILL]

Q)26. After a few weeks' experience, apprentice jewelers can usually begin to discriminate, though not with absolute certainty, genuine diamonds from imitation diamonds.
[A] genuine diamonds from imitation diamonds
genuine diamonds apart from imitations
[C] between genuine diamonds and imitation diamonds
[D] among genuine diamonds and imitation diamonds
[E] whether diamonds are imitation or genuine

Elimination rule between a and c

[vk_vinayak]

Q)26. After a few weeks' experience, apprentice jewelers can usually begin to discriminate, though not with absolute certainty, genuine diamonds from imitation diamonds.
[A] genuine diamonds from imitation diamonds
genuine diamonds apart from imitations
[C] between genuine diamonds and imitation diamonds
[D] among genuine diamonds and imitation diamonds
[E] whether diamonds are imitation or genuine

Elimination rule between a and c

The question tests the usage of the idiom. The correct idiom is Discriminate between X and Y. A doesn't follow this usage, hence A is incorrect.

[Krabhay]

a. 'Discrimination' doesn't take 'from' as a preposition with it.
b. Same error as 'a'.
c. 'Discrimination' takes 'against', 'on', 'between', 'among', 'as' and 'by' as prepositions along with it. So, option 'c' is grammatically true.
d. 'among' should be used for more than two people or things.
e. 'Whether' doesn't go with 'Discrimination'.
Hence, c is the answer.