The correct answer is mound of stones.
B. heap of stones
The correct answer is (B) Heap of stones piled up as a tombstone, memorial, landmark, etc. A pyramid of rough stones constructed to serve as a marker, etc.
Cairn comes from Gaelic carn (an elevation), Middle English carn.
Examples of use:
- A cairn marked the location of the grave.
- He uses a cairn to designate each corner of his property.