Which of the following is the BEST tool for a technician to use to make sure the network cable is securely fastened in the RJ-45 connector?

A cable tester verifies the wiring continuity and pin mapping of a finished cable but plays no role in physically securing the RJ-45 connector.

A crimping tool applies controlled mechanical force to deform the metal contacts inside an RJ-45 plug down onto the individual conductors and also compresses the strain relief boot onto the cable jacket, creating a permanent and secure connection. Without crimping, the conductors are loose inside the plug and will not maintain reliable contact. This is the only tool specifically designed for this termination task.

A small flat screwdriver has no mechanism to compress RJ-45 contacts onto conductors and would damage the connector.

A punch down tool is designed for IDC-style terminations in wall jacks and patch panels, not for modular RJ-45 plugs.