You configured a trunk between Switch A and Switch B. Everything works as expected, except you cannot pass traffic for VLAN 9. Which command will fix the issue without causing network interruption? Refer to the following exhibit.

A. SwitchB(config-if)#switchport trunk allowed vlan 1-1001
B. SwitchB(config-if)#switchport trunk allowed vlan all
C. SwitchB(config-if)#switchport trunk allowed vlan remove 9
D. SwitchB(config-if)#switchport trunk allowed vlan add 9

D. Although switchport trunk allowed vlan all and switchport trunk allowed vlan 1-1001 would rectify the problem, it would cause network interruption if those VLANs were blocked for security concerns. The proper way to add a VLAN is switchport trunk allowed vlan add 9.