a company that markets air fresheners has a series of commercials about being "nose-blind," that is, people getting used to odors such as those from pets or cooking pungent foods to the extent that they no longer notice them. "nose-blindness" is actually

Habituation

Explanation: Habituation is defined as mechanism in which the person tends to reduce the response towards the stimulus due to prolonged interaction or presentation with it. It is kind of learning process that gets settles due to the repeated exposure.

The case mentioned in the question also wants to refer "nose-blindness" towards the odor as habituation because people are repeatedly exposed to the same odor that they don't notice the fragrance of their air fresheners.

answer; (c) on the left side; ; ; ; ; ; ; ; ; ; ; ; ; speech is localized on the left side of the brain;

rain should be the answer.