Please choose the correct ending to complete the given sentence: Computers and Electronics: [header] How to choose devices for testing your mobile app [title] Define your app's specifications. [step] If your app is suitable for specific screen resolutions, sizes, etc. , include only the devices that support these features.

Ending1: You should also confirm your device supports these features by researching the device manufacturer and reading the suggested user requirements. [substeps] Your website may offer some background information on the devices you will be testing, but if you do not have a complete list of users, search for the manufacturer's name online. Ending2: Above all, you want to stick to the optimum specifications. [substeps] If you use more than 12 devices, let them each have their own set of features. Ending3: [title] Make a list of the most popular devices among your app's users. [step] If your app is just going to be released and there's no stats available, check similar apps. Ending4: [title] Confirm your app's compatibility with the operating system you want to test. [title] Check whether your app is at the right device by finding the app app's address on the device list.

Answer format: ending1/ending2/ending3/ending4