Why Are Test Items on an Experimental Form of a Standardized

Why are test items on an experimental form of a standardized test analyzed?

A) To see how many test items are needed.
B) To see if they discriminate between students at different grade levels.
C) To see if they are too easy or too hard.
D) To see if there are questions that should be eliminated or added.
E) A, B, & C
F) B, C, & D