If we don't have the text then we can't really answer.
Because she is going to school exactly at 9 a.m.
Intrinsic motivation is a motivation "from inside", with internal, rather than external awards.
Three of the things you mentioned have an external reward: the 500 Dollar prize( first option), the credit (third) and the hope of winning a blue ribbon (the last).
Only the second one has an intrinsic motivation: that you will be happy about performing this song (feeling proud of yourself, etc).
So here are the answers!
1. Left
2. had trekked
3. had visited
4. couldn't
5. bigger
The first three are in psst tense because the events did not happen just now, and could wouldn't make sense for number 4, and number 5, and biggest is not a word.
I've read this, surprisingly! The answer is D.