Martin,

Your question has nothing to do with T-SQL.

It's a task from school math.

To find the correct answer you need:

- stop browsing Internet for it;

- take a piece of paper;

- draw a time line on it;

- mark all time intervals from the table on the time line;

- mark the search interval on the same line.

Draw several different variations of the picture: with overlapping intervals, with one search interval covering several table intervals, etc.

Allocate 5 minutes of your time to analyze the pictures and figure out what are the criteria for selecting the right intervals.

I'm pretty sure you can find the answer.