Which of the following is a difference between Android and iOS operating systems?

Android device screen sizes vary enormously and many Android devices are larger than iOS devices, so the claim that iOS screens are larger is factually incorrect.

iOS is a closed-source proprietary operating system developed by Apple; it is Android that is open source (based on AOSP).

NFC is available on a wide range of Android devices and is used for features like Android Pay and contactless pairing, so stating Android lacks NFC is factually incorrect.

Android is based on an open-source Linux kernel and allows users to install APK files from any source, including third-party app stores and direct downloads, by enabling the 'Unknown sources' or 'Install unknown apps' setting. iOS, being a closed proprietary system, enforces an App Store-only distribution model (except via enterprise or developer profiles), preventing installation from other sources. This openness is a fundamental architectural difference between the two platforms.