PEJORATIVE
I. The individual may be classified as incomplete, immature, or by other pejorative terms which detract from his dignity.
II. If you make pejorative remarks in front of your customers, it is highly likely they will not return to your business.
III. Driver is a pejorative , invented by taxi drivers to describe a person who drives his private car instead of employing a chauffeur.

PEJORATIVE: A word expressing contempt, disapproval, insult (noun); Expressing contempt or disapproval or suggesting that something is not good or is of no importance (adjective). Statement I uses the word as an adjective correctly. In statement II, 'pejorative' is used as an adjective; the use of 'pejorative' is correct here as it explains that the customer may not return to business if the subject makes a derogatory remark in front of the customers. In statement III, the use of 'pejorative' is correct; the sentence mentions that 'pejorative' is used as a noun, a word made by taxi drivers to describe a kind of a person. Hence, option (a) is the correct answer.