For sensors measuring from 100°C to 250°C which one would be the most accurate between the followings A sensor with an error of 1 of the span A sensor with an error of 2 of the reading A sensor with 1

The sensor with an error of 1% of the span would be the most accurate for measuring temperatures from 100°C to 250°C. This means that the sensor's error is based on the full range of temperatures it is measuring, rather than just the current reading. The other two options have errors that are based on the current reading, which can lead to larger inaccuracies as the temperature increases.