I want add condition for certain question in Commcare, but want it to display when I choice specific option from Lookup Table options
@Hassienh_Obead :
In the display condition of that question, you can use the following condition :
selected(, "your_valid_value")
Refer this : https://help.commcarehq.org/display/commcarepublic/CommCare+Functions#CommCareFunctions-selected