Because it's the number of "temperatures" (or rather the 1-degree increments between them) on the thermometer. Which you just counted by drawing an arrow to each one. It's the right answer to the question they didn't realize they were asking. 💯 A+
(I appreciate that the teacher wrote "?" thus giving the child an opportunity to explain their answer, and see if they could provide the conventional answer if given a better prompt!)
Well, if you ace the autism test it means you have autism, meaning you want it. If you fail the autism test, it means you are being troubled by the condition of having autism, and were administered the test to verify if your troubles are stemming from autism.
Usually the tests are not given to people that can successfully mask and be classified as "high functioning". Implying that if you are interfacing with the autism test, it's usually not to see if your excellent programming skills stem from autism, more likely why you tend to be put in distress when lights give off a hum while you wear a wool sweater.
This particular example would be the person failing the test, because instead of correctly assuming the question was to get you to match the numbers to the correct part on the image, you failed by following instructiones too literally.
They were supposed to draw arrows from the numbers at the bottom to their place on the thermometer. Context is there, but they certainly should have shown an example or worded it differently.