Thanks for the question! Let’s take a look at what we’re being asked here. We want to come up with something that has to be true if salaries have kept pace with rising prices during the past year.
Well, what do we know from the stimulus? We can diagram it basically as
Decrease in revenues —> Attitudes change v Prices rise Attitudes change —> Celebrate Prices rise —> ~Salaries keep pace
And so we now know that salaries actually did keep pace. Well, take the contrapositive of the last statement, which gets us
Salaries keep pace —> ~Prices rise
So now we know prices don’t rise. And that’s what (C) says, so we can pick it and move on. (B) doesn't follow because it's still possible that the attitudes changed, and only one of the two needs to happen.
Hope this helps! Feel free to ask any other questions that you might have.