Final answer:
The privacy approach where the researcher does not know the identity of the participants is known as anonymity. Confidentiality is different as it involves the researcher knowing the identity but maintaining its secrecy.
Step-by-step explanation:
The approach to privacy that ensures even the researcher is not aware of the identity of the participant is anonymity. Anonymity means that the personal details of participants are not known to anyone, including the researchers. In contrast, confidentiality involves the researcher knowing the participants' identities but being bound by ethical and legal constraints to keep that information private and not disclose it to others. In research, ensuring participant privacy is crucial for ethical standards, and decisions around anonymity or confidentiality are governed by an institutional review board (IRB), research ethics committees, or similar bodies.