Which of the following actions would be LEAST likely to reduce resource contention?

Answer: Disable transparent memory page sharing.

Explanation:
A virtual machine connected to certain devices, like a serial or parallel port or a CD-ROM drive, can use some CPU resources. So it might be possible to reduce resource contention slightly by disconnecting from these devices. However, disabling transparent memory page sharing would reduce the amount of physical memory available to virtual machines, actually increasing the likelihood of resource contention, making that option the lease likely to reduce contention.
Transparent memory page sharing is performed by the ESX Host and is transparent to the virtual machine, therefore a limit at the virtual machine level would be ineffective.