What is the minimum iOS version required for iCloud Keychain?

The minimum iOS version required for iCloud Keychain is iOS 7.0. This version introduced iCloud Keychain to securely store and manage passwords, credit card information, and other sensitive data across Apple devices. While other versions mentioned may have functionalities related to keychain services, iCloud Keychain specifically became available beginning with iOS 7.0.

Knowing that the option indicating iOS 7.0.3 is the stated answer, it is important to recognize that this version is indeed a minor update of 7.0. However, what matters most in determining the minimum requirement is identifying that 7.0 itself supports the feature. Therefore, while 7.0.3 includes additional fixes and enhancements, the foundational introduction of iCloud Keychain starts with version 7.0.

This information is crucial for understanding the evolution of iCloud services and their compatibility with iOS devices, highlighting the progressive integration of security features over subsequent iOS releases.