________ is a unique representation of a subject engaged in an online transaction.Group of answer choicesAuthenticatorCredentialTokenDigital Identity

The correct answer is Digital Identity.

Explanation

A digital identity is a set of data that uniquely represents an individual or entity engaged in online transactions. This representation includes various attributes such as username, password, and other personal information that can verify the identity of the user in the digital world. It is crucial for secure online interactions, as it ensures that parties can validate each other’s identities, thereby reducing the risk of fraud and identity theft in digital environments.

In contrast, other options like authenticator and credential are related terms but do not represent the entire scope of a person's identity online. A token is often a temporary key for authentication rather than a complete representation. Thus, Digital Identity is the most fitting term in the context provided.