The question requires modifying an existing network trunk from the bash shell. The tmsh utility is used for this purpose. The correct command is modify, as the trunk already exists. Trunks are network-level objects, so they reside under the /net module within tmsh. The syntax interfaces add {1.3 1.4} correctly appends the specified interfaces to the existing list of members for the trunk named trunkA.

B. tmsh modify /sys trunk trunkA interfaces add {1.3 1.4}

This is incorrect because network trunks are configured within the /net module, not the /sys module, which is for system-level settings.

C. tmsh create /net trunk trunkA interfaces add {1.3 1.4}

This is incorrect because the create command is used for new objects. The question specifies modifying an existing trunk.

D. tmsh create /sys trunk trunkA interfaces add {1.3 1.4}

This is incorrect for two reasons: it uses the create command for an existing object and references the wrong module (/sys instead of /net).

1. F5 Networks, BIG-IP TMOS Command Line Interface Reference, Version 16.1.

Section: net trunk

Content: This document explicitly details the syntax for managing network trunks. The modify command is shown for altering existing trunk properties. The example syntax for adding interfaces is modify /net trunk [name] { interfaces add { [interfacename] ... } }, which directly validates the structure of the correct answer.

2. F5 Networks, BIG-IP LTM Device Management, Version 16.1.

Chapter: Trunks

Section: Creating and Managing Trunks

Content: This guide explains that trunks are network objects used to aggregate bandwidth. While focusing on GUI configuration, it establishes the object's place within the network configuration hierarchy, reinforcing that it belongs under the /net module in tmsh, not /sys.