¿Cómo dirías “you all were saving up money”? a)ahorraba dinero
b)ahorrabas dinero
c)ahorraban dinero
d)ahorrábamos dinero

c) ahorraban dinero

Explanation:

Because in spanish aborraban means to save up when you are talking about a group of people that doesn't include yourself. or it can be used to talk at group of people, like you all or y'all.

a) is wrong because it talking about one person or speaking to one person in a formal way of saying you.

b) is wrong because it is using the you ending, in an informal way.

d) is wrong because it is talking about we or us in a group.

So c is the right answer.