Compartmentalization is the best defense-in-depth implementation for protecting high value assets or for handling environments that have trust concerns because it is a strategy that divides the network or system into smaller segments or compartments, each with its own security policies, controls, and access rules. Compartmentalization helps to isolate and protect the most sensitive or critical data and functions from unauthorized or malicious access, as well as to limit the damage or impact of a breach or compromise. Compartmentalization also helps to enforce the principle of least privilege, which grants users or processes only the minimum access rights they need to perform their tasks. Therefore, compartmentalization is the correct answer.