Which security option is best for granting temporary read access to data in an Azure Storage account?

The best option for granting temporary read access to data in an Azure Storage account is Shared Access Signatures (SAS). SAS provides a secure way to provide limited access to Azure Storage resources without exposing the account key. With SAS, you can define specific permissions such as read, write, or delete for a specified period. This means you can grant temporary access to a user or application while ensuring that they only have access to what's necessary for their task.

This temporary access is time-bound, meaning it can automatically expire after a certain duration, enhancing security by limiting how long external entities can access your data. Additionally, SAS tokens can be created with varying levels of permissions tailored to the needs of the user, making it a flexible solution for granting access.

In contrast, options like CORS Support are meant for enabling cross-origin requests in a web environment and do not provide access control features for users. The Storage Account option would involve sharing the entire account, which is not advisable due to security concerns. Network rules are used primarily to control which network traffic can access your storage account but do not provide a mechanism for temporary and controlled access to specific resources within the account.