What constitutes forgery in legal terms?

The legal definition of forgery primarily revolves around the act of signing someone else's name without their permission, particularly when this is done with the intent to deceive or defraud. The correct choice highlights this definition by specifying the act of signing the name of another without authority or intent to defraud. This captures the essence of forgery, which not only involves the unauthorized signature but also implies a deceptive purpose.

In legal contexts, the act of forgery is often pursued because it can lead to various forms of fraud, so establishing the intent to defraud is crucial. This choice aligns straightforwardly with statutory definitions and case law surrounding forgery, making it the most accurate representation of what constitutes this crime.

The other options do not align with the legal definition of forgery. For instance, signing a document with permission is not forgery, as it is done with the requisite authority. Creating a fake identification and altering a legal contract might involve fraudulent actions, but they each pertain to specific criminal offenses rather than the fundamental nature of forgery itself.