alguem pode me ajudar? fiquei com duvida se era C mesmo

Turn the sentence below into IMPERSONAL PASSIVE: People say dogs live longer than cats *

a- People used to say that dogs live longer than cats
b- Dogs live longer than cats by said to people.
c- It is said that dogs live longer than cats
d- It is people say that dogs live longer than cats
e- It is said to people say that dogs live longer than cats