In Denver, Colorado there is a 10% probability of snow on a specific day. How was this probability most likely determined? On days with similar conditions as this day, it has snowed 10% of the time in Denver, Colorado.

On this day each year, it snowed 10% of the time.

On days with similar conditions as this day, it has snowed 10% of the time in Colorado.

During this month, it snowed 10% of the days.

The probability was determined randomly.