After playing tennis, Lori hurries home because her mother always bakes Lori's favorite brownies on Saturday afternoons. As Lori opens the front door, she notices the kitchen trashcan smells horribly, but her mother says, "I don't smell anything." The most likely explanation for this is that Lori's mother

She has a higher absolute threshold (for smells).

Explanation:

The absolute threshold is the minimum detectable level of stimulus. It applies for other senses such as ear, whose threshold can be measured using a gradually increasing frequency.

A low threshold indicates more sensibility (a dog has a lower smell threshold than humans). The higher the threshold, the more difficult we find it to detect a stimulus.