You write a SQL Server stored procedure that will return data for a report. The accuracy of the data is not so important; however, you want to avoid dirty reads. Which isolation level should you avoid?

Read Uncommitted isolation level allows dirty reads - it can read data that has been modified but not committed by other transactions. Since the requirement is to avoid dirty reads, this is the isolation level to avoid. Read Committed, Repeatable Read, and Serializable all prevent dirty reads at varying levels of strictness.