Final answer:
To secure a load balancer against basic threats, the network technician should disable unnecessary services, reducing the attack surface and minimizing vulnerabilities.
Step-by-step explanation:
The fundamental step a network technician should take to secure the load balancer against basic threats is B. Disable unnecessary services on the load balancer. By disabling services that are not needed for the load balancer's operation, the potential attack surface is reduced. This minimizes the number of potential vulnerabilities that could be exploited by attackers. It is an essential security practice to keep only the necessary ports and services active and to secure those that are in use with strong configurations and updated security patches.