Which feature should a network engineer enable within a mixed-client network to ensure that the legacy client operates at the best possible rates?

Cisco ClientLink is a proprietary technology designed to improve the performance of 802.11a/g legacy clients in an 802.11n/ac network by using transmit beamforming to enhance the signal quality to these older clients. This technology helps legacy devices achieve better data rates and extended range, even without their own MIMO capabilities.

RRM (Radio Resource Management) is a Cisco feature that automatically adjusts AP power and channel settings to optimize overall network performance and minimize interference for all clients, not specifically targeting legacy client rates.

DCA (Dynamic Channel Assignment) is a component of RRM focused on assigning optimal channels to access points to avoid interference, which does not directly improve data rates for legacy clients.

Band Select encourages dual-band clients to connect to the 5 GHz band over the 2.4 GHz band, which does not address improving the performance of legacy clients, many of which may operate solely on 2.4 GHz.