What does Microsoft consider the most important performance counter to be used to detect memory bott

What does Microsoft consider the most important performance counter to be used to detect
memory bottlenecks?

A.
Disk pages/second

B.
Disk pagedefaults/second

C.
Disk pagefaults/minute

D.
Disk pages/minute

Explanation:
Reference: http://technet.microsoft.com/en-us/library/cc749872.aspx
Memory Bottlenecks and Paging
If you suspect a memory shortage, chart the following Performance Monitor counters:
Memory: Page Faults/sec
Memory: Pages Input/sec

Memory: Page Reads/sec