Which Apple service allows users to back up their data in the cloud?

iCloud is the service that enables users to securely back up their data in the cloud. It provides a seamless experience for users across Apple devices, allowing them to store documents, photos, videos, and other important information. With iCloud, users can easily access their data from any device connected to their Apple ID, ensuring that their information is not only safe but also readily available whenever needed.

Additionally, iCloud offers features like automatic backups for iOS devices, meaning that critical data can be backed up without manual intervention, thereby minimizing the risk of data loss. This service is particularly valuable for users who may switch devices or need to restore their data after a device reset or hardware failure.

Other options, while they may sound plausible, do not represent recognized services offered by Apple. Apple's branding aligns closely with iCloud for cloud storage and backup solutions, emphasizing that iCloud is the correct choice for backing up data in the cloud.