问题：

[单选]

A client/server application has been configured to use local naming. The client and server run on separate machines. When the client tries to connect， it receives a TNS error. By carefully examining the environment， a tnsnames.ora is found only on the Oracle server machine， among other things. After copying this tnsnames.ora onto the client machine， the client is able to connect to the server. 
Which statement is true？（）

A . tnsnames.ora must be on the client machine for local naming. 
B . tnsnames.ora must be removed from the server for the connection to work. 
C . tnsnames.ora must be on both the client and server machines for local naming. 
D . tnsnames.ora is not required for local naming; the problem was not fixed by copying the file to the client.