Answer:
Last summer, when school started, after winter break, yesterday, is the correct answer.
Step-by-step explanation:
The order of elements seems to start today (the present) and the closest past is yesterday; a little bit farther away, there is after the winter break. Since schools start after summer, next one (still going backwards) is when school started; finally, the farthest one in time is last summer, which seems to indicate the beginning of the events.