The number of users under the OLT can also determine whether the VLA adopts single-layer or double-layer VLAN mode. Single-layer VLAN can be used when the number of users is small, and double-layer VLAN must be used when the need to differentiated services and the number of users is second to ().
A . 2K
B . 4K
C . SK
D . 1K
Answer: B