@maamoun96_m, try this, this should solve your issue:
In the survey tab of your xlsform:
In the choices tab of your xlsform:
Data entry as seen in Enketo:
Reference xlsform:
a53Cefm5esemXTYMRTMPRr.xlsx (11.7 KB)
Note: Have a look closer at the if-statement
. I have removed the '
from the calculation expression that solved the issue.