Where would you see footprints that happen due to dirt being left behind inside?\nOptions:\n- roof\n- ground\n- rug\n- surface of earth\n- floorboards
Please answer the following question by reasoning step-by-step.
rug
Footrpints on rugs can be seen only when foot left behind the dirt on rug.

Peple walk on rug usually.

.

So, the final answer is rug