answer:
either b.haría or a.hacen because technically both are correct
explanation:
a.hacen
in english the sentence is "i'd do everything if it didn't work."
b.haría
in english the sentence is "i would do everything if it didn't work."
c.hice
in english the sentence is "
i did everything if it didn't work."
good luck :)
i hope this helps
have a nice day !!
