The correct answer is 'Hacktivist' because the primary motivation of the attacks is to promote political beliefs regarding animal rights, rather than for financial gain or data exfiltration. Hacktivists often publicize their actions to draw attention to a cause or to effect change, which aligns with the attackers' behavior in this scenario. Other threat actors like 'Nation-state' or 'Organized crime' entities would be improbable due to the lack of espionage or financial motives. 'Insider threat' does not fit the pattern, as there is no indication that the attackers are internal members of the organization. 'Shadow IT' relates to unauthorized IT systems within an organization, not external threats. Lastly, 'Unskilled attacker' suggests a lack of capability or sophistication, which does not necessarily apply in this context.