Which isolation level should you use?

You are developing an application that reads and writes data from a SQL Server database.
You need to ensure transactional data integrity.
Which isolation level should you use?

A.
Serializable

B.
ReadCommitted

C.
ReadUncommitted

D.
Normal

Explanation:
Serializable provides the highest level of data integrity.
https://msdn.microsoft.com/en-us/library/system.data.isolationlevel(v=vs.110)