The correct option is A his bad habits have
The tense of a sentence denotes a time, whether it is the time now (present), time then (past) or the time to come (future). The verb of a sentence has most to do with the tense. In the given sentence, a verb form of the suitable tense is required, the speaker states a result of 'his bad habits'. The most suitable option is B, as these 'habits' have ruined him and his family, this is in the present perfect tense. This tense describes an action that began in the past and completed near the present, 'have ruined', hence option B is correct. 'Are' is used in the present continuous tense, to describe an action that is going on at the moment, 'are' is followed by the main verb, the present participle (a verb that ends in -ing). The correct form would be 'are ruining', but the sentence has a past participle, 'ruined', hence option A is incorrect. 'Did' is usually used in negative and interrogative statements, and is followed by a base form, 'ruin', but the sentence is an affirmative one, and has a past participle 'ruined', hence option C is incorrect. Option D is incorrect because the right option is B.