To determine on which day she would use a positive number to write the temperature, we would typically consider a context where temperatures could be both above and below zero. In many regions, if the temperature is above freezing (e.g., above 0 degrees Celsius or above 32 degrees Fahrenheit), a positive number would be used.
Without additional context about the temperatures for each day, I can't definitively say which day corresponds to a positive temperature. However, if you know the specific temperatures for each day, look for the day with a temperature above zero to find the correct response.
If you want to proceed with the options provided, it's likely a matter of guessing unless you have specific temperature data. If you have any additional details or numbers about the temperatures for each day, feel free to share, and I can help analyze the situation. Otherwise, consider checking your knowledge or any resources available to you regarding this question's context.