Answer:
it is true that an app can not be used on device with different operating system
Step-by-step explanation:
app cannot be used on device with different operating system is true
because app may may be having different versions that is available for the different operating systems and different platforms
because there are different operating system like Symbian OS , iOS , BlackBerry OS and window etc
so every operating system have have unique language code for which an app is design
so it is true that an app can not be used on device with different operating system