Correct alternative: A) When / While.
"While and When" are Past Continuous' Time Markers, and they can perfectly be used to indicate an action in progress, at the same time of another one.
While:
Ex.: I was doing my homework while the phone was ringing.
Translation: Eu estava fazendo minha lição de casa enquanto o telefone estava tocando.
Or, ex.: While the phone was ringing, I was doing my homework.
Translation: Enquanto o telefone estava tocando, eu estava fazendo minha lição de casa.
You can perfectly change the place of "while" without changing the meaning. But you've got to add a coma ( , ) if you start the sentence with "while". You can invert the order of the sentences too.
With "while", both sentences (before and after "while") will be in Past Continuous.
"While" means "Enquanto".
When:
Ex.: I was doing my homework when the phone rang.
Translation: Eu estava fazendo minha lição de casa quando o telefone tocou.
Or, ex.: When the phone rang, I was doing my homework.
Translation: Quando o telefone tocou, eu estava fazendo minha lição de casa.
You can perfectly change the place of "when" without changing the meaning. But you've got to add a coma ( , ) if you start the sentence with "when". You can invert the order of the sentences too.
With "when", there will be always an interrupted action, and the action which is interrupting the other action.
The interrupted action will always be in Past Continuous, and the action which is interrupting the other action will always be in Past Simple or Past Perfect, but commonly in Past Simple.
In this case, the interrupted action is "I was doing my homework", and the action which is interrupting other action is "the phone rang", because it's interrupting the action "I was doing my homework".
"When" means "Quando".
Hope I've helped, enjoy your studies!
