Final answer:
The theft and release of internal political party communications to aid an opposing party is an activity most indicative of Advanced Persistent Threats (APTs), which are typically well-resourced and sophisticated actors like nation-states or state-sponsored groups.
Step-by-step explanation:
The situation described in the question involves a hacker breaching a major political party's server, stealing internal communications related to campaign strategies, and releasing them to benefit the opposition party. Among the provided options, this behavior is best categorized as an action of Advanced Persistent Threats (APTs). APTs are a category of cyber threats where the intruder, often a nation-state or state-sponsored group, gains unauthorized access to a network and remains undetected for an extended period.
APTs are characterized by their sophistication, persistence, and significant resources, which can include advanced levels of knowledge and significant funding. They are methodical in their approach and often target high-profile entities such as government organizations or major corporations for espionage or political motives. Unlike other hacker profiles like semi-authorized hackers, script kiddies, or state actors, APTs maintain long-term access to networks, which aligns with the described scenario, where the unauthorized access to the political party's network has been leveraged strategically.