The correct answer is 'Vishing'. Vishing, or voice phishing, involves an attacker using the telephone system in an attempt to scam the user into disclosing private information by pretending to be a legitimate entity, in this case, the company's IT department. Email phishing is incorrect as it specifically refers to the use of emails for scamming users. Smishing involves sending text messages, which is not the case here. Moreover, Pretexting generally refers to a scenario where an attacker comes up with a fabricated scenario to steal information, but the key difference lies in the means, which here is a phone call characteristic of vishing.