A layer 2 switch is used to switch incoming frames from a 1000base-t port to a port connected to a 100base-t network. which method of memory buffering would work best for this task?

Shared memory buffering would work best. This would give the ports the best allocation of resources, using only those that are the most active and best allocated for the size of the frames being transmitted in the current traffic. In addition, any port can store these frames, instead of being specifically allocated as per other types of memory buffering.