Final answer:
The sentence describing temperature is a quantitative observation since it gives a specific numeric value measuring the temperature in degrees Celsius.
Step-by-step explanation:
The sentence "the temperature outside is 250 C" is an example of a quantitative observation. This is because it provides a numeric value that measures the temperature in degrees Celsius. Qualitative observations, on the other hand, would describe qualities or characteristics that are not expressed as numbers, such as saying the temperature is 'hot' or 'chilly'. In contrast, quantitative data is specific and measurable, and in this case, tells us exactly how hot it is outside with a numerical value.