You have a storage account named storage1 that contains a blob container named container1. You must ensure new blobs added to container1 cannot be modified for one year. Which setting should you configure?

An access policy, specifically an immutable blob storage policy (also known as a time-based retention policy or legal hold), is the correct setting. This policy ensures that blobs cannot be modified or deleted for a specified duration, such as one year, once they are written. This is crucial for compliance and data integrity. The access tier (Hot, Cool, Archive) relates to storage cost and performance, not immutability. Access control (IAM) settings manage who can access the storage account and its resources, not the immutability of the data itself. The access level (Private, Blob, Container) defines how public the container and its blobs are, not their immutability.