Which of the following is NOT one of the four varieties of Hebrew graves?

The correct answer is the variety of graves labeled as a vault. In the context of Hebrew burial practices, the four main types of graves typically recognized include chamber graves, trench graves, and bench graves.

Chamber graves are complete rooms carved into rock or earth, often allowing for multiple burials. Trench graves are deeper and longer, accommodating several bodies in a single excavation. Bench graves are characterized by ledges or benches where the deceased may be laid, often found in tomb-like structures.

The term "vault" commonly refers to a burial structure that is enclosed and typically made to prevent ground collapse, which is not aligned with the traditional forms of Hebrew graves. Thus, this classification does not fit within the customary varieties recognized in Hebrew burial customs.