You create an application by using Microsoft Visual Studio .NET 2008 and the .NET Framework 3.5.
The application connects to a Microsoft SQL Server 2005 database by using LINQ to SQL. The database contains a table named MarketTransaction.
The MarketTransaction records must be validated against certain business rules before they are added to or updated in the database.
You need to design a validation strategy for the MarketTransaction records. You also need to ensure that the schema changes do not affect the validation code.
What should you do?

A.
Implement validation as an OnValidate static extension method to the MarketTransaction class.

B.
Implement validation in a new partial class that implements the OnValidate method as a partial method.

C.
Implement validation by adding an OnValidate method in the MarketTransaction class inside the .cs file that is generated by LINQ to SQL.

D.
Implement validation by creating a new business logic class named MarketTransactionBL.
Design this class to inherit the MarketTransaction class and implement an OnValidate method.