Use reasoning to lead to the answer of the following question:
The person wanted to use her ear to detect the buffalo herd, where did she put it?
Options:
- on the buffalo
- person's head
- side of head
- ground
- serial killer's bedroom
 Reasoning process:
When buffalo herd arriving from far you can hear noise putting ears on ground. Runnning buffalo herd makes large impact on ground. Therefore, the final answer is ground.