Respuesta :
Were ringing is the answer.
That is because it shows that an ongoing action was happening in the past tense form.
Answer: b. were ringing
That is because it shows that an ongoing action was happening in the past tense form.
Answer: b. were ringing
Will be rung because it's future tense, but shall ring dies not make any sense and it's a command. It's not the rest are not correct because they have no helping verb.