I guess the Question poster just went strictly by what was "written" in BOL 😉

ms-help://MS.SQLCC.v9/MS.SQLSVR.v9.en/sqlexprbol/html/279fe698-5107-4891-b669-b04217ee421e.htm

But the description clearly says:

Shared Memory

Lets you connect to an instance of SQL Server that is running on the same computer. Cannot be used for access from other computers on the network

So the real answer is 3 😀

Just my $0.02