tenant or the landlord or threatening to inflict such harm with the present ability to effect the harm and under circumstances which would lead a reasonable person to believe that such threat will be carried out, (B) substantial and wilful destruction of part of the dwelling unit or premises, (C) conduct which presents an immediate and serious danger to the safety of other tenants or the landlord, or (D) using the premises or allowing the premises to be used for prostitution or the illegal sale of drugs or, in the case of a housing authority, using any area within fifteen hundred feet of any housing authority property in which the tenant resides for the illegal sale of drugs. If the landlord elects to evict based upon an allegation, pursuant to subsection (g) of section 47a-11, that the tenant failed to require other persons on the premises with his consent to conduct themselves in a manner that will not constitute a serious nuisance, and the tenant claims to have had no knowledge of such conduct, then, if the landlord establishes that the premises or, in the case of a landlord that is a housing authority, the premises or any area within fifteen hundred feet of any housing authority property in which the tenant resides has been used for the illegal sale of drugs, the burden shall be on the tenant to show that he had no knowledge of the creation of the serious nuisance.