In which type of Megalith (grave/memorial) were the stone pieces set in a circular shape around the grave?

Cairn circle

The correct answer is Option 1- Cairn circle

The type of megalith with stone pieces set in a circular shape around the grave is called a cairn circle.

Cairn circles are prehistoric monuments that are found all over the world. They are typically made up of a ring of standing stones, with a burial chamber in the center. The burial chamber may be a simple cist (a stone box) or a more complex structure, such as a dolmen.

Cairn circles were used for a variety of purposes, including burial, ritual, and territorial marking. They are also thought to have been used as astronomical observatories.