View the Exhibit and examine the output of the query. 
What do you infer from this?
A.The SGA_TARGET is a static parameter.
B.The instance is started, but the database is not yet open.
C.The server parameter file (SPFILE) was used to start the instance.
D.The SGA_TARGET parameter does not have any effect on the database instance until the SGA_MAX_SIZE parameter is specified.
V$SPPARAMETER 显示 SPFILE 相关的内容，如果所有的行都是 FALSE，则代表没启用 SPFILE。