Which performance object should you add to the counter log?

TestKing.com has a server named SQL1 that runs SQL Server 2005 Enterprise Edition.
SQL1 has 2 GB of RAM, 1.6 GB of which are used by the default SQL Server database engine instance. The average data growth of all databases combined is 100 MB a month.
Users state that report execution times are increasing. You want to assess whether more RAM is needed.
You need to use System Monitor to create a counter log that will help you decide whether to add RAM. Which performance object should you add to the counter log?

A.
MSAS 2005:Cache

B.
MSAS 2005:Memory

C.
MSAS 2005:Proactive Caching

D.
SQLServer:Buffer Manager

E.
SQLServer:SQL Statistics

F.
SQLServer:General Statistics

Explanation:
The SQL Server:Buffer Manager object will show you – Low Buffer cache hit ration – Low Page life expectancy – High number of Checkpoint pages/sec – High number Lazy writes/sec

Insufficient memory and I/O overhead are usually related bottlenecks. SQLServer performance depends heavily on the I/O subsystem. Unless your database fits into physical memory, SQLServer constantly brings database pages in and out of the buffer pool. This generates substantial I/O traffic. Similarly, the log records need to be flushed to the disk before a transaction can be declared committed. And finally, SQLServer uses tempdb for various purposes such as to store intermediate results, to sort, to keep row versions and so on. So a good I/O subsystem is critical to the performance of SQLServer.