Comprehensive and Detailed Explanation:

The correct answer is A — Disconnect / Refresh / Reconnect / Authenticate / Synchronize.

Before refreshing a Salesforce sandbox that is connected to Marketing Cloud, you must first Disconnect the integration. Otherwise, the link between MC and Salesforce could break.

Then, Refresh the Salesforce sandbox (refreshing rebuilds a copy of the production org).

After the refresh, you Reconnect Marketing Cloud to the refreshed Salesforce sandbox.

Authenticate again (OAuth) to ensure permissions and tokens are up-to-date.

Finally, Synchronize objects and data.

❌ Why others are wrong:

Other options either refresh before disconnecting or sync/authenticate in the wrong order, which could cause major connection errors.

Exact Extract from Salesforce Official Documentation:

Salesforce Help — Refresh Salesforce Sandbox with Marketing Cloud Connect:

"Disconnect Marketing Cloud from the Salesforce Sandbox before refreshing it. After refreshing, reconnect, authenticate, and synchronize your settings and data extensions."

(Source: https://help.salesforce.com/s/articleView?id=sf.mc_co_sandbox_refresh.htm )

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