Measurement A shows neck size.
Measurement B shows head circumference. Remember to include the ears!
Below the picture there is also a video with instructions for measurement. Neck size is measured around the center of the neck with a finger in between. The largest circumference around the head is measured spaciously from under the chin and OVER THE EARS with the ears tilted FORWARD. If you have a dog with horizontal ears, measure spaciously over the ears from under the chin.
NOTE: The video is texted in Norwegian.