You need to stop a blocking process that has an SPID of 64 without stopping other processes

You administer a Microsoft SQL Server 2012 instance.
You need to stop a blocking process that has an SPID of 64 without stopping other processes.
What should you do?

A.
Execute the following Transact-SQL statement:
EXECUTE sp_KillSPID 64

B.
Restart the SQL Server service.

C.
Execute the following Transact-SQL statement:
KILL 64

D.
Execute the following Transact-SQL statement:
ALTER SESSION KILL ’64’

Explanation:
Reference: http://msdn.microsoft.com/en-us/library/ms173730.aspx