You are creating a Windows application by using the .NET Framework 3.5.
The application will be used for processing sales orders.
Individual product quantities are retrieved from the database before an order is placed. The product
quantity is reduced after an order is placed.
You need to design a concurrency model to ensure that the correct product quantity on hand is displayed
at all times.
What should you do?

A.
Use a DataReader object to retrieve the quantity on hand. When an order is placed, verify whether the
quantity on hand for the particular product in the database has decreased.

B.
Use a DataSet object and a DataAdapter object to retrieve the quantity on hand. When an order is
placed, verify whether the quantity on hand for the particular product in the database has decreased.

C.
Use a Transaction object along with the IsolationLevel property set to IsolationLevel.Serializable. Read
and update the quantity on hand within the Transaction object for each product.

D.
Use a Transaction object along with the IsolationLevel property set to IsolationLevel.ReadCommitted.
Read and update the quantity on hand within the Transaction object for each product.