You are creating two user-defined functions (UDFs) of Excel Services in Microsoft Office SharePoint Server 2007.

You write the following code segment.

public class Class1
{
public double MyDouble (double d)
{
return d * 9;
}
public DateTime ReturnDateTimeToday ()
{
return ( DateTime.Today );
}
}

You need to ensure that the MyDouble method and the ReturnDateTimeToday method are recognized as UDFs of Excel Services. What should you do?

A.
Add a reference to the Excel Services DLL.

B.
Change the methods from public to private.

C.
Add an out parameter to each of the method statements.

D.
Mark the class by using the UdfClass attribute and mark the methods by using the UdfMethod attribute.