Answer E is correct. A new column can be created that does not allow NULL content as long as a default value is also supplied.
For more information, see the following sources:
Chapter 2, "Creating Database Objects," and Chapter 3, "Implementing Database Objects"
SQL Server 2005 Books Online: "SQL Server Database Engine, Designing and Creating Databases, Tables, Designing Tables, Enforcing Data Integrity"
"ALTER TABLE," http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_aa-az_3ied.asp