Answer:
4
Step-by-step explanation:
We need to find the length of the blue line. It is obviously shorter than the line marked with length of 6. This means we can rule out 10 and 8, which are answers larger than 6. This leaves us with answers 2 and 4. 2 is two small compared to the segment at the bottom, and therefore the answer is 4.
We can check that it indeed is 4 because it is similar length to the segment marked as 3, but a little longer.
I hope this helped! :)
