During peak operating hours, an Administrator finds that a business critical application is not performing as well as during normal hours. Which of the following memory management methods could be used to guarantee the application performs well at all times?

A.
Set the Share level to High for the virtual machine running the application and set all other virtual machines to Low

B.
Set a Reservation equal to the Peak Memory utilization of the virtual machine running the application

C.
Set the Share level to High for the virtual machine running the application

D.
Set a Reservation equal to the Average Memory utilization of the virtual machine running the application

Explanation:
Memory Provisioning Recommendations for VMware Infrastructure 3 Operational Best Practices page 8.

Memory Reservations, Limits, and Shares
Memory Reservations are an ESX Server memory management technique used to control how memory is allocated from an either an explicit or implicit resource pool by the VMkernel to a virtual machine or group of virtual machines.
Reservations consist of two settings a reservation, or guaranteed amount of physical memory that will always be available to the virtual machine(s), and a limit, which is the absolute maximum physical memory a virtual machine or group of virtual machines can consume on the host During peak operating hours, by definition more systems and more resources including memory, will be being consumed. Therefore memory reservation is required. By setting a reservation equal to the peak memory utilization, this will guarantee the application receives all memory it requires.