Which Is True Regarding the Item Characteristic Curve, or "S

Multiple Choice

Which is true regarding the item characteristic curve, or "S" curve, in Item Response Theory (IRT) ?

A) It assumes that as people's abilities increase, their probability of answering the item correctly decreases.
B) A tall "S" means that an item has difficulty discriminating across ability.
C) IRT and the S curve assist in writing items to target specific ranges of ability.
D) It is useful in predicting the Standard Error of the Estimate.