Test item cannot discriminate low achievers and high achievers when its value is lower than?

Test item cannot discriminate low achievers and high achievers when its value is lower than?

(a) 0.30-1
(b) 0.30
(c) 1
(d) None
✅ Correct option: (b) 0.30
Explanation: Below 0.30, an item fails to differentiate student performance levels.