Which of these is a type of ancient Egyptian tomb in the form of a rectangular structure?

A mastaba is a type of ancient Egyptian tomb in the form of a flat-roofed, rectangular structure with inward sloping sides, constructed out of mud-bricks (from the Nile River). These edifices marked the burial sites of many eminent Egyptians during Egypt's Early Dynastic Period and Old Kingdom. In the Old Kingdom epoch, local kings began to be buried in pyramids instead of in mastabas, although non-royal use of mastabas continued for over a thousand years. Egyptologists call these tombs mastaba, from the Arabic word مصطبة "stone bench".

The afterlife was an important part of Ancient Egyptian religion. This is reflected in their architecture and most prominently by the enormous amounts of time, money, and labour involved in the building of tombs. Ancient Egyptians believed the soul could live only if the body was preserved from corruption and depredation as well as fed.

Starting in the Predynastic era and continuing into the later dynasties, the ancient Egyptians developed increasingly complex and effective methods for preserving and protecting the bodies of the dead. They buried their dead in pit graves dug out from the sand; the body placed on a mat, usually along with some items believed to help them in the afterlife. The first tomb structure which the Egyptians developed was the mastaba, composed of earthen bricks made from soil along the Nile. It provided better protection from scavenging animals and from grave robbers.