The correct answer is A. d'azu. The question is asking which of the options is not an imperative (umurtau) verb. D'azu is a verb in the prohibitive form, meaning "don't go" or "don't do", whereas the other options - kwanta (lie down), tafi (go), tashi (stand up), and zauna (sit down) - are all imperative verbs, used to give commands or instructions. Therefore, the correct answer is A. d'azu, as it is the only prohibitive verb among the options.