Is it a, b, c or d? Please help

a. The hog farmer does not notice the barn smell from the working boots when he  wears them on the porch of the house.

Explanation:

The hog farmer does not notice the barn smell from the working boots when he  wears them on the porch of the house is the example of sensory adaptations. Sensory adaptation is a decrease in sensitivity to a stimulus after regular exposure to it. So the farmer can't smell his own boots due to regular exposure to the smell so we can say that it is an example of sensory adaptations..