Which statement is true about the relationship between the amount of plant food remaining and the number of days?

1. This relationship is a function because only one amount of plant food remains each day.
2. This relationship is not a function because more than one amount of plant food remains each day.
3. This relationship is a function because more than one amount of plant food remains each day.
4. This relationship is not a function because only one amount of plant food remains each day.