Select all the situations for which only zero or positive solutions make sense. (Select all that apply.)
1. Measuring temperature in degrees Celsius at an Arctic outpost each day in January.
2. The height of a candle as it burns over an hour.
3. The elevation above sea level of a hiker descending into a canyon.
4. The number of students remaining in school after 6:00 p. m.
5. The temperature in degrees Fahrenheit of an oven used on a hot summer day.