What is the purpose of a signal pharse

What is the best way to change the sentence below from active voice to passive voice? [ presenters give awards to the winners at the elaborate ceremony held every year] a. the awards are given at an elaborate ceremony held every year. b. the ceremony where someone gives the winner awards every year is elaborate. c. somebody gives winners an award at the elaborate ceremony held every year. d. an elaborate ceremony held every year is where presenters give out awards.