Rule reminder
Bureaucratic Italian ('burocratese') relies heavily on nominal style: fixed expressions like 'in ottemperanza a', 'ai sensi di', 'a norma di', 'con riferimento a', 'in relazione a', 'si comunica che', 'si precisa che', 'si fa presente che'. Verbs are replaced by their deverbal nouns, and the passive / impersonal is obligatory.
Which sentence is the most appropriate opening for an official administrative letter?